Psychology is the

scientific Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

study of mind and behavior. Psychology includes the study of

conscious Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...

and

unconscious Unconscious may refer to: Physiology * Unconsciousness, the lack of consciousness or responsiveness to people and other environmental stimuli Psychology * Unconscious mind, the mind operating well outside the attention of the conscious mind a ...

phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between the

natural Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

and

social science Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of so ...

s. Psychologists seek an understanding of the emergent properties of

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

s, linking the discipline to

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...

. As social scientists, psychologists aim to understand the behavior of individuals and groups.Fernald LD (2008)
''Psychology: Six perspectives''
(pp.12–15). Thousand Oaks, CA: Sage Publications.Hockenbury & Hockenbury. Psychology. Worth Publishers, 2010. Ψ (''psi''), the first

letter Letter, letters, or literature may refer to: Characters typeface * Letter (alphabet), a character representing one or more of the sounds used in speech; any of the symbols of an alphabet. * Letterform, the graphic form of a letter of the alphabe ...

of the Greek word ''psyche'' from which the term psychology is derived (see below), is commonly associated with the science. A professional practitioner or researcher involved in the discipline is called a psychologist. Some psychologists can also be classified as behavioral or

cognitive scientists Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...

. Some psychologists attempt to understand the role of mental functions in individual and

social behavior Social behavior is behavior among two or more organisms within the same species, and encompasses any behavior in which one member affects the other. This is due to an interaction among those members. Social behavior can be seen as similar to an ...

. Others explore the physiological and neurobiological processes that underlie cognitive functions and behaviors. Psychologists are involved in research on

perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...

, cognition, attention,

emotion Emotions are mental states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or suffering, displeasure. There is currently no scientific ...

intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be des ...

, subjective experiences, motivation, brain functioning, and

personality Personality is the characteristic sets of behaviors, cognitions, and emotional patterns that are formed from biological and environmental factors, and which change over time. While there is no generally agreed-upon definition of personality, m ...

. Psychologists' interests extend to

interpersonal relationship The concept of interpersonal relationship involves social associations, connections, or affiliations between two or more people. Interpersonal relationships vary in their degree of intimacy or self-disclosure, but also in their duration, in t ...

psychological resilience Psychological resilience is the ability to cope mentally or emotionally with a crisis or to return to pre-crisis status quickly. The term was coined in the 1970s by a psychologist named Emmy E. Werner as she conducted a forty year long study o ...

, family resilience, and other areas within

social psychology Social psychology is the scientific study of how thoughts, feelings, and behaviors are influenced by the real or imagined presence of other people or by social norms. Social psychologists typically explain human behavior as a result of the ...

. They also consider the unconscious mind.

Psychoanalysis PsychoanalysisFrom Greek: + . is a set of theories and therapeutic techniques"What is psychoanalysis? Of course, one is supposed to answer that it is many things — a theory, a research method, a therapy, a body of knowledge. In what might b ...

and other forms of

depth psychology Depth psychology (from the German term ''Tiefenpsychologie'') refers to the practice and research of the science of the unconscious, covering both psychoanalysis and psychology. It is also defined as the psychological theory that explores the rel ...

are most typically associated with theories about the unconscious mind. By contrast,

behaviorist Behaviorism is a systematic approach to understanding the behavior of humans and animals. It assumes that behavior is either a reflex evoked by the pairing of certain antecedent stimuli in the environment, or a consequence of that individual ...

s consider such phenomena as

classical conditioning Classical conditioning (also known as Pavlovian or respondent conditioning) is a behavioral procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a triangle). It also refers to the learni ...

and operant conditioning. Cognitivists explore

implicit memory In psychology, implicit memory is one of the two main types of long-term human memory. It is acquired and used unconsciously, and can affect thoughts and behaviours. One of its most common forms is procedural memory, which allows people to perfo ...

automaticity Automaticity is the ability to do things without occupying the mind with the low-level details required, allowing it to become an automatic response pattern or habit. It is usually the result of learning, repetition, and practice. Examples of tas ...

, and

subliminal message Subliminal stimuli (; the prefix ' literally means "below" or "less than") are any sensory stimuli below an individual's threshold for conscious perception, in contrast to stimuli (above threshold). A 2012 review of functional magnetic resonanc ...

s, all of which are understood either to bypass or to occur outside of conscious effort or attention. Indeed, cognitive-behavioral therapists counsel their clients to become aware of maladaptive thought patterns, the nature of which the clients previously had not been conscious. Research psychologists employ empirical methods to infer

causal Causality (also referred to as causation, or cause and effect) is influence by which one event, process, state, or object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the ca ...

and correlational relationships between psychosocial variables. Some, but not all, clinical and counseling psychologists rely on symbolic interpretation. While psychological knowledge is often applied to the assessment and treatment of mental health problems, it is also directed towards understanding and solving problems in several spheres of human activity. By many accounts, psychology ultimately aims to benefit society.O'Neil, H.F.; cited in Coon, D.; Mitterer, J.O. (2008)
''Introduction to psychology: Gateways to mind and behavior''
(12th ed., pp. 15–16). Stamford, CT: Cengage Learning."The mission of the APA merican Psychological Associationis to advance the creation, communication and application of psychological knowledge to benefit society and improve people's lives"; APA (2010)
''About APA''.
Retrieved 20 October 2010. Many psychologists are involved in some kind of therapeutic role, practicing psychotherapy in clinical, counseling, or

school A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes comp ...

settings. Other psychologists conduct scientific research on a wide range of topics related to mental processes and behavior. Typically the latter group of psychologists work in academic settings (e.g., universities, medical schools, or hospitals). Another group of psychologists is employed in industrial and organizational settings. Yet others are involved in work on

human development Human development may refer to: * Development of the human body * Developmental psychology * Human development (economics) * Human Development Index, an index used to rank countries by level of human development * Human evolution Human evoluti ...

, aging,

sports Sport pertains to any form of competitive physical activity or game that aims to use, maintain, or improve physical ability and skills while providing enjoyment to participants and, in some cases, entertainment to spectators. Sports can, ...

, health, forensic science,

education Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty ...

, and the

media Media may refer to: Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Broadcast media, communications delivered over mass e ...

Etymology and definitions

The word ''

psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...

'' derives from the Greek word ''psyche'', for spirit or

soul In many religious and philosophical traditions, there is a belief that a soul is "the immaterial aspect or essence of a human being". Etymology The Modern English noun '' soul'' is derived from Old English ''sāwol, sāwel''. The earliest atte ...

. The latter part of the word "psychology" derives from -λογία ''-logia'', which refers to "study" or "research".Online Etymology Dictionary. (2001)
"Psychology"
. The

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''psychologia'' was first used by the

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

humanist Humanism is a philosophical stance that emphasizes the individual and social potential and agency of human beings. It considers human beings the starting point for serious moral and philosophical inquiry. The meaning of the term "human ...

and Latinist

Marko Marulić Marko Marulić Splićanin (), in Latin Marcus Marulus Spalatensis (18 August 1450 – 5 January 1524), was a Croatian poet, lawyer, judge, and Renaissance humanist who coined the term "psychology". He is the national poet of Croatia. According to ...

in his book, ''

Psichiologia de ratione animae humanae ''Psichiologia de ratione animae humanae'' ( Croatian: ''Psihologija, o naravi ljudske duše'')Steven Blankaart in 1694 in ''The Physical Dictionary''. The dictionary refers to "Anatomy, which treats the Body, and Psychology, which treats of the Soul."(Steven Blankaart, p. 13) as quoted in "psychology n." A Dictionary of Psychology. Edited by Andrew M. Colman. Oxford University Press 2009. Oxford Reference Online. Oxford University Press
oxfordreference.com
In 1890,

William James William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States. James is considered to be a leading thinker of the lat ...

defined ''psychology'' as "the science of mental life, both of its phenomena and their conditions." This definition enjoyed widespread currency for decades. However, this meaning was contested, notably by radical behaviorists such as

John B. Watson John Broadus Watson (January 9, 1878 – September 25, 1958) was an American psychologist who popularized the scientific theory of behaviorism, establishing it as a psychological school.Cohn, Aaron S. 2014.Watson, John B." Pp. 1429–1430 in ''T ...

, who in 1913 asserted that the discipline is a "natural science", the theoretical goal of which "is the prediction and control of behavior." Since James defined "psychology", the term more strongly implicates scientific

experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into Causality, cause-and-effect by demonstrating what outcome oc ...

ation.

Folk psychology In philosophy of mind and cognitive science, folk psychology, or commonsense psychology, is a human capacity to explain and predict the behavior and mental state of other people. Processes and items encountered in daily life such as pain, pleasure ...

refers to ordinary people's, as contrasted with psychology professionals', understanding of the mental states and behaviors of people.

History

The ancient civilizations of Egypt, Greece, China, India, and Persia all engaged in the philosophical study of psychology. In Ancient Egypt the Ebers Papyrus mentioned depression and thought disorders. Historians note that Greek philosophers, including

Thales Thales of Miletus ( ; grc-gre, Θαλῆς; ) was a Greek mathematician, astronomer, statesman, and pre-Socratic philosopher from Miletus in Ionia, Asia Minor. He was one of the Seven Sages of Greece. Many, most notably Aristotle, regarded ...

Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

, and

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...

(especially in his ''

De Anima ''On the Soul'' ( Greek: , ''Peri Psychēs''; Latin: ''De Anima'') is a major treatise written by Aristotle c. 350 BC. His discussion centres on the kinds of souls possessed by different kinds of living things, distinguished by their differen ...

'' treatise), addressed the workings of the mind. As early as the 4th century BC, the Greek physician

Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history o ...

theorized that

mental disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...

s had physical rather than supernatural causes. In 387 BCE, Plato suggested that the brain is where mental processes take place, and in 335 BCE Aristotle suggested that it was the heart. In China, psychological understanding grew from the philosophical works of Laozi and

Confucius Confucius ( ; zh, s=, p=Kǒng Fūzǐ, "Master Kǒng"; or commonly zh, s=, p=Kǒngzǐ, labels=no; – ) was a Chinese philosopher and politician of the Spring and Autumn period who is traditionally considered the paragon of Chinese sages. C ...

, and later from the doctrines of

Buddhism Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religions, Indian religion or Indian philosophy#Buddhist philosophy, philosophical tradition based on Pre-sectarian Buddhism, teachings attributed to the Buddha. ...

. This body of knowledge involves insights drawn from introspection and observation, as well as techniques for focused thinking and acting. It frames the universe in term of a division of physical reality and mental reality as well as the interaction between the physical and the mental. Chinese philosophy also emphasized purifying the mind in order to increase virtue and power. An ancient text known as '' The Yellow Emperor's Classic of Internal Medicine'' identifies the brain as the nexus of wisdom and sensation, includes theories of personality based on yin–yang balance, and analyzes mental disorder in terms of physiological and social disequilibria. Chinese scholarship that focused on the brain advanced during the

Qing Dynasty The Qing dynasty ( ), officially the Great Qing,, was a Manchu-led imperial dynasty of China and the last orthodox dynasty in Chinese history. It emerged from the Later Jin dynasty founded by the Jianzhou Jurchens, a Tungusic-spea ...

with the work of Western-educated Fang Yizhi (1611–1671), Liu Zhi (1660–1730), and Wang Qingren (1768–1831). Wang Qingren emphasized the importance of the brain as the center of the nervous system, linked mental disorder with brain diseases, investigated the causes of dreams and

insomnia Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...

, and advanced a theory of hemispheric lateralization in brain function.Yeh Hsueh and Benyu Guo, "China", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). Influenced by

Hinduism Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global p ...

Indian philosophy Indian philosophy refers to philosophical traditions of the Indian subcontinent. A traditional Hindu classification divides āstika and nāstika schools of philosophy, depending on one of three alternate criteria: whether it believes the Veda ...

explored distinctions in types of awareness. A central idea of the ''

Upanishads The Upanishads (; sa, उपनिषद् ) are late Vedic Sanskrit texts that supplied the basis of later Hindu philosophy.Wendy Doniger (1990), ''Textual Sources for the Study of Hinduism'', 1st Edition, University of Chicago Press, , ...

'' and other

Vedic upright=1.2, The Vedas are ancient Sanskrit texts of Hinduism. Above: A page from the '' Atharvaveda''. The Vedas (, , ) are a large body of religious texts originating in ancient India. Composed in Vedic Sanskrit, the texts constitute the ...

texts that formed the foundations of Hinduism was the distinction between a person's transient mundane self and their eternal, unchanging soul. Divergent Hindu doctrines and

have challenged this hierarchy of selves, but have all emphasized the importance of reaching higher awareness.

Yoga Yoga (; sa, योग, lit=yoke' or 'union ) is a group of physical, mental, and spiritual practices or disciplines which originated in ancient India and aim to control (yoke) and still the mind, recognizing a detached witness-consci ...

encompasses a range of techniques used in pursuit of this goal. Theosophy, a religion established by

Russian-American Russian Americans ( rus, русские американцы, r=russkiye amerikantsy, p= ˈruskʲɪje ɐmʲɪrʲɪˈkant͡sɨ) are Americans of full or partial Russian ancestry. The term can apply to recent Russian immigrants to the United Stat ...

philosopher

Helena Blavatsky Helena Petrovna Blavatsky, uk, Олена Петрівна Блаватська, Olena Petrivna Blavatska (; – 8 May 1891), often known as Madame Blavatsky, was a Russian mystic and author who co-founded the Theosophical Society in 187 ...

, drew inspiration from these doctrines during her time in

British India The provinces of India, earlier presidencies of British India and still earlier, presidency towns, were the administrative divisions of British governance on the Indian subcontinent. Collectively, they have been called British India. In one ...

.Anand C. Paranjpe, "From Tradition through Colonialism to Globalization: Reflections on the History of Psychology in India", in Brock (ed.), ''Internationalizing the History of Psychology'' (2006).PT Raju (1985), Structural Depths of Indian Thought, State University of New York Press, , pages 35-36 Psychology was of interest to Enlightenment thinkers in Europe. In Germany,

Gottfried Wilhelm Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of math ...

(1646–1716) applied his principles of calculus to the mind, arguing that mental activity took place on an indivisible continuum. He suggested that the difference between conscious and unconscious awareness is only a matter of degree. Christian Wolff identified psychology as its own science, writing ''Psychologia Empirica'' in 1732 and ''Psychologia Rationalis'' in 1734.

Immanuel Kant Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and ...

advanced the idea of

anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of be ...

as a discipline, with psychology an important subdivision. Kant, however, explicitly rejected the idea of an experimental psychology, writing that "the empirical doctrine of the soul can also never approach chemistry even as a systematic art of analysis or experimental doctrine, for in it the manifold of inner observation can be separated only by mere division in thought, and cannot then be held separate and recombined at will (but still less does another thinking subject suffer himself to be experimented upon to suit our purpose), and even observation by itself already changes and displaces the state of the observed object." In 1783, Ferdinand Ueberwasser (1752–1812) designated himself ''Professor of Empirical Psychology and Logic'' and gave lectures on scientific psychology, though these developments were soon overshadowed by the

Napoleonic Wars The Napoleonic Wars (1803–1815) were a series of major global conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European states formed into various coalitions. It produced a period of Fren ...

. At the end of the Napoleonic era, Prussian authorities discontinued the Old University of Münster. Having consulted philosophers Hegel and Herbart, however, in 1825 the Prussian state established psychology as a mandatory discipline in its rapidly expanding and highly influential

educational system The educational system generally refers to the structure of all institutions and the opportunities for obtaining education within a country. It includes all pre-school institutions, starting from family education, and/or early childhood education ...

. However, this discipline did not yet embrace experimentation.Horst U.K. Gundlach, "Germany", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). In England, early psychology involved phrenology and the response to social problems including alcoholism, violence, and the country's crowded "lunatic" asylums.

Beginning of experimental psychology

Philosopher John Stuart Mill believed that the human mind was open to scientific investigation, even if the science is in some ways inexact. Mill proposed a "mental chemistry" in which elementary thoughts could combine into ideas of greater complexity.

Gustav Fechner Gustav Theodor Fechner (; ; 19 April 1801 – 18 November 1887) was a German physicist, philosopher, and experimental psychologist. A pioneer in experimental psychology and founder of psychophysics (techniques for measuring the mind), he ins ...

began conducting psychophysics research in

Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as ...

in the 1830s. He articulated the principle that human perception of a stimulus varies

logarithmically In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 o ...

according to its intensity. The principle became known as the

Weber–Fechner law The Weber–Fechner laws are two related hypotheses in the field of psychophysics, known as Weber's law and Fechner's law. Both laws relate to human perception, more specifically the relation between the actual change in a physical stimulus an ...

. Fechner's 1860 ''Elements of Psychophysics'' challenged Kant's negative view with regard to conducting quantitative research on the mind. Fechner's achievement was to show that "mental processes could not only be given numerical magnitudes, but also that these could be measured by experimental methods." In Heidelberg,

Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz (31 August 1821 – 8 September 1894) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The Helmholtz Associatio ...

conducted parallel research on sensory perception, and trained physiologist Wilhelm Wundt. Wundt, in turn, came to Leipzig University, where he established the psychological

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physic ...

that brought experimental psychology to the world. Wundt focused on breaking down mental processes into the most basic components, motivated in part by an analogy to recent advances in chemistry, and its successful investigation of the elements and structure of materials.Stanford Encyclopedia of Philosophy. (2006)
"Wilhelm Maximilian Wundt"
. Paul Flechsig and

Emil Kraepelin Emil Wilhelm Georg Magnus Kraepelin (; ; 15 February 1856 – 7 October 1926) was a German psychiatrist. H. J. Eysenck's ''Encyclopedia of Psychology'' identifies him as the founder of modern scientific psychiatry, psychopharmacology and psych ...

soon created another influential laboratory at Leipzig, a psychology-related lab, that focused more on experimental psychiatry. The German psychologist Hermann Ebbinghaus, a researcher at the

University of Berlin Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative ...

, was another 19th-century contributor to the field. He pioneered the experimental study of memory and developed quantitative models of learning and forgetting. In the early twentieth century, Wolfgang Kohler,

Max Wertheimer Max Wertheimer (April 15, 1880 – October 12, 1943) was an Austro-Hungarian psychologist who was one of the three founders of Gestalt psychology, along with Kurt Koffka and Wolfgang Köhler. He is known for his book, ''Productive Thinking'', and ...

, and

Kurt Koffka Kurt Koffka (March 12, 1886 – November 22, 1941) was a German psychologist and professor. He was born and educated in Berlin, Germany; he died in Northampton, Massachusetts from coronary thrombosis. He was influenced by his maternal uncle, ...

co-founded the school of

Gestalt psychology Gestalt-psychology, gestaltism, or configurationism is a school of psychology that emerged in the early twentieth century in Austria and Germany as a theory of perception that was a rejection of basic principles of Wilhelm Wundt's and Edward ...

(not to be confused with the

Gestalt therapy Gestalt therapy is a form of psychotherapy that emphasizes personal responsibility and focuses on the individual's experience in the present moment, the therapist–client relationship, the environmental and social contexts of a person's life ...

Fritz Perls Friedrich Salomon Perls (July 8, 1893 – March 14, 1970), better known as Fritz Perls, was a Germany, German-born psychiatrist, psychoanalyst and psychotherapist. Perls Neologism, coined the term "Gestalt therapy" to identify the form of psychoth ...

). The approach of Gestalt psychology is based upon the idea that individuals experience things as unified wholes. Rather than reducing thoughts and behavior into smaller component elements, as in structuralism, the Gestaltists maintained that whole of experience is important, and differs from the sum of its parts. Psychologists in Germany, Denmark, Austria, England, and the United States soon followed Wundt in setting up laboratories.

G. Stanley Hall Granville Stanley Hall (February 1, 1846 – April 24, 1924) was a pioneering American psychologist and educator. His interests focused on human life span development and evolutionary theory. Hall was the first president of the American Psy ...

, an American who studied with Wundt, founded a psychology lab that became internationally influential. The lab was located at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consi ...

. Hall, in turn, trained Yujiro Motora, who brought experimental psychology, emphasizing psychophysics, to the Imperial University of Tokyo.Miki Takasuna, "Japan", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). Wundt's assistant, Hugo Münsterberg, taught psychology at Harvard to students such as Narendra Nath Sen Gupta—who, in 1905, founded a psychology department and laboratory at the

University of Calcutta The University of Calcutta (informally known as Calcutta University; CU) is a public collegiate state university in India, located in Kolkata, West Bengal, India. Considered one of best state research university all over India every year, ...

. Wundt's students Walter Dill Scott,

Lightner Witmer Lightner Witmer (June 28, 1867 – July 19, 1956) was an American psychologist. He introduced the term " clinical psychology" and is often credited with founding the field that it describes. Witmer created the world's first "psychological clinic" ...

, and James McKeen Cattell worked on developing tests of mental ability. Cattell, who also studied with

eugenicist Eugenics ( ; ) is a fringe set of beliefs and practices that aim to improve the genetic quality of a human population. Historically, eugenicists have attempted to alter human gene pools by excluding people and groups judged to be inferior or ...

Francis Galton, went on to found the Psychological Corporation. Witmer focused on the mental testing of children; Scott, on employee selection. Another student of Wundt, the Englishman Edward Titchener, created the psychology program at

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

and advanced " structuralist" psychology. The idea behind structuralism was to analyze and classify different aspects of the mind, primarily through the method of

introspection Introspection is the examination of one's own conscious thoughts and feelings. In psychology, the process of introspection relies on the observation of one's mental state, while in a spiritual context it may refer to the examination of one's sou ...

. William James, John Dewey, and Harvey Carr advanced the idea of functionalism, an expansive approach to psychology that underlined the Darwinian idea of a behavior's usefulness to the individual. In 1890, James wrote an influential book, ''

The Principles of Psychology ''The Principles of Psychology'' is an 1890 book about psychology by William James, an American philosopher and psychologist who trained to be a physician before going into psychology. There are four methods from James' book: stream of consciousne ...

'', which expanded on the structuralism. He memorably described "

stream of consciousness In literary criticism, stream of consciousness is a narrative mode or method that attempts "to depict the multitudinous thoughts and feelings which pass through the mind" of a narrator. The term was coined by Daniel Oliver in 1840 in ''First L ...

." James's ideas interested many American students in the emerging discipline. Dewey integrated psychology with societal concerns, most notably by promoting

progressive education Progressive education, or protractivism, is a pedagogical movement that began in the late 19th century and has persisted in various forms to the present. In Europe, progressive education took the form of the New Education Movement. The term ''pr ...

, inculcating moral values in children, and assimilating immigrants. One of Pavlov's dogs

A different strain of experimentalism, with a greater connection to physiology, emerged in South America, under the leadership of Horacio G. Piñero at the

University of Buenos Aires The University of Buenos Aires ( es, Universidad de Buenos Aires, UBA) is a public research university in Buenos Aires, Argentina. Established in 1821, it is the premier institution of higher learning in the country and one of the most prestigi ...

. In Russia, too, researchers placed greater emphasis on the biological basis for psychology, beginning with

Ivan Sechenov Doctor Ivan Mikhaylovich Sechenov (russian: Ива́н Миха́йлович Се́ченов; , Tyoply Stan (now Sechenovo) near Simbirsk, Russia – , Moscow), was a Russian psychologist, physiologist, and medical scientist. The very fa ...

's 1873 essay, "Who Is to Develop Psychology and How?" Sechenov advanced the idea of brain reflexes and aggressively promoted a deterministic view of human behavior.Irina Sirotkina and Roger Smith, "Russian Federation", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). The Russian-Soviet physiologist

Ivan Pavlov Ivan Petrovich Pavlov ( rus, Ива́н Петро́вич Па́влов, , p=ɪˈvan pʲɪˈtrovʲɪtɕ ˈpavləf, a=Ru-Ivan_Petrovich_Pavlov.ogg; 27 February 1936), was a Russian and Soviet experimental neurologist, psychologist and physio ...

discovered in dogs a learning process that was later termed "

" and applied the process to human beings.

Consolidation and funding

One of the earliest psychology societies was ''La Société de Psychologie Physiologique'' in France, which lasted from 1885 to 1893. The first meeting of the International Congress of Psychology sponsored by the International Union of Psychological Science took place in Paris, in August 1889, amidst the World's Fair celebrating the centennial of the French Revolution. William James was one of three Americans among the 400 attendees. The

American Psychological Association The American Psychological Association (APA) is the largest scientific and professional organization of psychologists in the United States, with over 133,000 members, including scientists, educators, clinicians, consultants, and students. It ha ...

(APA) was founded soon after, in 1892. The International Congress continued to be held at different locations in Europe and with wide international participation. The Sixth Congress, held in Geneva in 1909, included presentations in Russian, Chinese, and Japanese, as well as Esperanto. After a hiatus for World War I, the Seventh Congress met in Oxford, with substantially greater participation from the war-victorious Anglo-Americans. In 1929, the Congress took place at Yale University in New Haven, Connecticut, attended by hundreds of members of the APA.Ludy T. Benjamin, Jr., and David B. Baker, "The Internationalization of Psychology: A History", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). Tokyo Imperial University led the way in bringing new psychology to the East. New ideas about psychology diffused from Japan into China. American psychology gained status upon the U.S.'s entry into World War I. A standing committee headed by Robert Yerkes administered mental tests ("

Army Alpha The Army Alpha is a group-administered test developed by Robert Yerkes and six others in order to evaluate the many U.S. military recruits during World War I. It was first introduced in 1917 due to a demand for a systematic method of evalua ...

" and " Army Beta") to almost 1.8 million soldiers. Subsequently, the

Rockefeller family The Rockefeller family () is an American industrial, political, and banking family that owns one of the world's largest fortunes. The fortune was made in the American petroleum industry during the late 19th and early 20th centuries by brot ...

, via the

Social Science Research Council The Social Science Research Council (SSRC) is a US-based, independent, international nonprofit organization dedicated to advancing research in the social sciences and related disciplines. Established in Manhattan in 1923, it today maintains a he ...

, began to provide funding for behavioral research. Rockefeller charities funded the National Committee on Mental Hygiene, which disseminated the concept of mental illness and lobbied for applying ideas from psychology to child rearing. Through the Bureau of Social Hygiene and later funding of

Alfred Kinsey Alfred Charles Kinsey (; June 23, 1894 – August 25, 1956) was an American sexologist, biologist, and professor of entomology and zoology who, in 1947, founded the Institute for Sex Research at Indiana University, now known as the Kinsey Insti ...

, Rockefeller foundations helped establish research on sexuality in the U.S. Under the influence of the Carnegie-funded Eugenics Record Office, the Draper-funded

Pioneer Fund Pioneer Fund is an American non-profit foundation established in 1937 "to advance the scientific study of heredity and human differences". The organization has been described as racist and white supremacist in nature. One of its first project ...

, and other institutions, the eugenics movement also influenced American psychology. In the 1910s and 1920s, eugenics became a standard topic in psychology classes.Guthrie, ''Even the Rat was White'' (1998), Chapter 4: "Psychology and Race" (pp. 88–110). "Psychology courses often became the vehicles for eugenics propaganda. One graduate of the Record Office training program wrote, 'I hope to serve the cause by infiltrating eugenics into the minds of teachers. It may interest you to know that each student who takes psychology here works up his family history and plots his family tree.' Harvard, Columbia, Brown, Cornell, Wisconsin, and Northwestern were among the leading academic institutions teaching eugenics in psychology courses." In contrast to the US, in the UK psychology was met with antagonism by the scientific and medical establishments, and up until 1939, there were only six psychology chairs in universities in England. During World War II and the Cold War, the U.S. military and intelligence agencies established themselves as leading funders of psychology by way of the armed forces and in the new Office of Strategic Services intelligence agency. University of Michigan psychologist Dorwin Cartwright reported that university researchers began large-scale propaganda research in 1939–1941. He observed that "the last few months of the war saw a social psychologist become chiefly responsible for determining the week-by-week-propaganda policy for the United States Government." Cartwright also wrote that psychologists had significant roles in managing the domestic economy. The Army rolled out its new

General Classification Test A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, and marines or naval infantry. In some usages the term "general officer" refers to a rank above colonel."general, adj. and n.". OED O ...

to assess the ability of millions of soldiers. The Army also engaged in large-scale psychological research of troop morale and mental health.Schonfeld, I.S., & Chang, C.-H. (2017). ''Occupational health psychology: Work, stress, and health''. New York, NY: Springer Publishing Company. In the 1950s, the Rockefeller Foundation and

Ford Foundation The Ford Foundation is an American private foundation with the stated goal of advancing human welfare. Created in 1936 by Edsel Ford and his father Henry Ford, it was originally funded by a US$25,000 gift from Edsel Ford. By 1947, after the death ...

collaborated with the

Central Intelligence Agency The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...

(CIA) to fund research on

psychological warfare Psychological warfare (PSYWAR), or the basic aspects of modern psychological operations (PsyOp), have been known by many other names or terms, including Military Information Support Operations (MISO), Psy Ops, political warfare, "Hearts and M ...

. In 1965, public controversy called attention to the Army's Project Camelot, the "Manhattan Project" of social science, an effort which enlisted psychologists and anthropologists to analyze the plans and policies of foreign countries for strategic purposes. In Germany after World War I, psychology held institutional power through the military, which was subsequently expanded along with the rest of the military during

Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...

. Under the direction of

Hermann Göring Hermann Wilhelm Göring (or Goering; ; 12 January 1893 – 15 October 1946) was a German politician, military leader and convicted war criminal. He was one of the most powerful figures in the Nazi Party, which ruled Germany from 1933 to 1 ...

's cousin Matthias Göring, the Berlin Psychoanalytic Institute was renamed the Göring Institute. Freudian psychoanalysts were expelled and persecuted under the anti-Jewish policies of the

Nazi Party The Nazi Party, officially the National Socialist German Workers' Party (german: Nationalsozialistische Deutsche Arbeiterpartei or NSDAP), was a far-right political party in Germany active between 1920 and 1945 that created and supported t ...

, and all psychologists had to distance themselves from Freud and Adler, founders of

psychoanalysis PsychoanalysisFrom Greek: + . is a set of theories and therapeutic techniques"What is psychoanalysis? Of course, one is supposed to answer that it is many things — a theory, a research method, a therapy, a body of knowledge. In what might b ...

who were also Jewish. The Göring Institute was well-financed throughout the war with a mandate to create a "New German Psychotherapy." This psychotherapy aimed to align suitable Germans with the overall goals of the Reich. As described by one physician, "Despite the importance of analysis, spiritual guidance and the active cooperation of the patient represent the best way to overcome individual mental problems and to subordinate them to the requirements of the ''

Volk The German noun ''Volk'' () translates to people, both uncountable in the sense of ''people'' as in a crowd, and countable (plural ''Völker'') in the sense of '' a people'' as in an ethnic group or nation (compare the English term '' folk ...

'' and the ''

Gemeinschaft ''Gemeinschaft'' () and ''Gesellschaft'' (), generally translated as "community and society", are categories which were used by the German sociologist Ferdinand Tönnies in order to categorize social relationships into two types. The Gesellschaft ...

''." Psychologists were to provide ''Seelenführung'' it., soul guidance the leadership of the mind, to integrate people into the new vision of a German community. Harald Schultz-Hencke melded psychology with the Nazi theory of biology and racial origins, criticizing psychoanalysis as a study of the weak and deformed. Johannes Heinrich Schultz, a German psychologist recognized for developing the technique of

autogenic training Autogenic training is a desensitization-relaxation technique developed by the German psychiatrist Johannes Heinrich Schultz by which a psychophysiologically determined relaxation response is obtained. The technique was first published in 1932. St ...

, prominently advocated sterilization and euthanasia of men considered genetically undesirable, and devised techniques for facilitating this process. After the war, new institutions were created although some psychologists, because of their Nazi affiliation, were discredited. Alexander Mitscherlich founded a prominent applied psychoanalysis journal called ''Psyche''. With funding from the Rockefeller Foundation, Mitscherlich established the first clinical psychosomatic medicine division at Heidelberg University. In 1970, psychology was integrated into the required studies of medical students. After the Russian Revolution, the

Bolsheviks The Bolsheviks (russian: Большевики́, from большинство́ ''bol'shinstvó'', 'majority'),; derived from ''bol'shinstvó'' (большинство́), "majority", literally meaning "one of the majority". also known in English ...

promoted psychology as a way to engineer the "New Man" of socialism. Consequently, university psychology departments trained large numbers of students in psychology. At the completion of training, positions were made available for those students at schools, workplaces, cultural institutions, and in the military. The Russian state emphasized

pedology Pedology (from Greek: πέδον, ''pedon'', "soil"; and λόγος, ''logos'', "study") is a discipline within soil science which focuses on understanding and characterizing soil formation, evolution, and the theoretical frameworks for modeling ...

and the study of child development.

Lev Vygotsky Lev Semyonovich Vygotsky (russian: Лев Семёнович Выго́тский, p=vɨˈɡotskʲɪj; be, Леў Сямёнавіч Выго́цкі, p=vɨˈɡotskʲɪj; – June 11, 1934) was a Soviet psychologist, known for his work on ps ...

became prominent in the field of child development. The Bolsheviks also promoted

free love Free love is a social movement that accepts all forms of love. The movement's initial goal was to separate the state from sexual and romantic matters such as marriage, birth control, and adultery. It stated that such issues were the concern ...

and embraced the doctrine of psychoanalysis as an antidote to sexual repression. Although pedology and intelligence testing fell out of favor in 1936, psychology maintained its privileged position as an instrument of the Soviet Union.

Stalinist purges The Great Purge or the Great Terror (russian: Большой террор), also known as the Year of '37 (russian: 37-й год, translit=Tridtsat sedmoi god, label=none) and the Yezhovshchina ('period of Yezhov'), was Soviet General Secreta ...

took a heavy toll and instilled a climate of fear in the profession, as elsewhere in Soviet society. Following World War II, Jewish psychologists past and present, including

, A.R. Luria, and Aron Zalkind, were denounced; Ivan Pavlov (posthumously) and Stalin himself were celebrated as heroes of Soviet psychology. Soviet academics experienced a degree of liberalization during the Khrushchev Thaw. The topics of cybernetics, linguistics, and genetics became acceptable again. The new field of engineering psychology emerged. The field involved the study of the mental aspects of complex jobs (such as pilot and cosmonaut). Interdisciplinary studies became popular and scholars such as Georgy Shchedrovitsky developed systems theory approaches to human behavior. Twentieth-century Chinese psychology originally modeled itself on U.S. psychology, with translations from American authors like William James, the establishment of university psychology departments and journals, and the establishment of groups including the Chinese Association of Psychological Testing (1930) and the Chinese Psychological Society (1937). Chinese psychologists were encouraged to focus on education and language learning. Chinese psychologists were drawn to the idea that education would enable modernization. John Dewey, who lectured to Chinese audiences between 1919 and 1921, had a significant influence on psychology in China. Chancellor T'sai Yuan-p'ei introduced him at Peking University as a greater thinker than Confucius. Kuo Zing-yang who received a PhD at the University of California, Berkeley, became President of

Zhejiang University Zhejiang University, abbreviated as ZJU or Zheda and formerly romanized as Chekiang University, is a national public research university based in Hangzhou, Zhejiang, China. It is a member of the prestigious C9 League and is selected into the n ...

and popularized behaviorism. After the

Chinese Communist Party The Chinese Communist Party (CCP), officially the Communist Party of China (CPC), is the founding and sole ruling party of the People's Republic of China (PRC). Under the leadership of Mao Zedong, the CCP emerged victorious in the Chinese Civil ...

gained control of the country, the Stalinist Soviet Union became the major influence, with

Marxism–Leninism Marxism–Leninism is a communist ideology which was the main communist movement throughout the 20th century. Developed by the Bolsheviks, it was the state ideology of the Soviet Union, its satellite states in the Eastern Bloc, and various c ...

the leading social doctrine and Pavlovian conditioning the approved means of behavior change. Chinese psychologists elaborated on Lenin's model of a "reflective" consciousness, envisioning an "active consciousness" () able to transcend material conditions through hard work and ideological struggle. They developed a concept of "recognition" () which referred to the interface between individual perceptions and the socially accepted worldview; failure to correspond with party doctrine was "incorrect recognition." Psychology education was centralized under the

Chinese Academy of Sciences The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republi ...

, supervised by the State Council. In 1951, the academy created a Psychology Research Office, which in 1956 became the Institute of Psychology. Because most leading psychologists were educated in the United States, the first concern of the academy was the re-education of these psychologists in the Soviet doctrines. Child psychology and pedagogy for the purpose of a nationally cohesive education remained a central goal of the discipline.

Disciplinary organization

Institutions

In 1920,

Édouard Claparède Édouard Claparède (24 March 1873 – 29 September 1940) was a Swiss neurologist, child psychologist, and educator. Career Claparède studied science and medicine, receiving in 1897 an MD from the University of Geneva, and working 1897–98 a ...

and Pierre Bovet created a new applied psychology organization called the International Congress of Psychotechnics Applied to Vocational Guidance, later called the International Congress of Psychotechnics and then the

International Association of Applied Psychology The International Association of Applied Psychology (IAAP) was created in 1919 by Édouard Claparède under the name of International Association of Psychotechnics (Association Internationale de Psychotechnique) and the secretary general was Jean ...

. The IAAP is considered the oldest international psychology association.Wade Pickren & Raymond D. Fowler, "Professional Organizations", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 1: ''History of Psychology''. Today, at least 65 international groups deal with specialized aspects of psychology. In response to male predominance in the field, female psychologists in the U.S. formed the National Council of Women Psychologists in 1941. This organization became the International Council of Women Psychologists after World War II and the International Council of Psychologists in 1959. Several associations including the Association of Black Psychologists and the Asian American Psychological Association have arisen to promote the inclusion of non-European racial groups in the profession. The International Union of Psychological Science (IUPsyS) is the world federation of national psychological societies. The IUPsyS was founded in 1951 under the auspices of the United Nations Educational, Cultural and Scientific Organization (UNESCO).Irmingard Staeuble, "Psychology in the Eurocentric Order of the Social Sciences: Colonial Constitution, Cultural Imperialist Expansion, Postcolonial Critique" in Brock (ed.), ''Internationalizing the History of Psychology'' (2006). Psychology departments have since proliferated around the world, based primarily on the Euro-American model. Since 1966, the Union has published the ''International Journal of Psychology''. IAAP and IUPsyS agreed in 1976 each to hold a congress every four years, on a staggered basis. IUPsyS recognizes 66 national psychology associations and at least 15 others exist. The American Psychological Association is the oldest and largest. Its membership has increased from 5,000 in 1945 to 100,000 in the present day.C. James Goodwin, "United States", in Baker (ed.), ''Oxford Handbook of the History of Psychology'' (2012). The APA includes 54 divisions, which since 1960 have steadily proliferated to include more specialties. Some of these divisions, such as the

Society for the Psychological Study of Social Issues Founded in 1936, the Society for the Psychological Study of Social Issues (SPSSI) is a group of 3,000 scientists from psychology and related fields who share a common interest in research on the psychological aspects of important social and policy i ...

and the American Psychology–Law Society, began as autonomous groups. The Interamerican Psychological Society, founded in 1951, aspires to promote psychology across the Western Hemisphere. It holds the Interamerican Congress of Psychology and ha had 1,000 members in year 2000. The European Federation of Professional Psychology Associations, founded in 1981, represents 30 national associations with a total of 100,000 individual members. At least 30 other international organizations represent psychologists in different regions. In some places, governments legally regulate who can provide psychological services or represent themselves as a "psychologist." The APA defines a psychologist as someone with a doctoral degree in psychology.Judy E. Hall and George Hurley, "North American Perspectives on Education, Training, Licensing, and Credentialing", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 8: ''Clinical Psychology''.

Boundaries

Early practitioners of experimental psychology distinguished themselves from

parapsychology Parapsychology is the study of alleged psychic phenomena (extrasensory perception, telepathy, precognition, clairvoyance, psychokinesis (also called telekinesis), and psychometry) and other paranormal claims, for example, those related to near ...

, which in the late nineteenth century enjoyed popularity (including the interest of scholars such as William James). Some people considered parapsychology to be part of "psychology." Parapsychology, hypnotism, and psychism were major topics at the early International Congresses. But students of these fields were eventually ostracized, and more or less banished from the Congress in 1900–1905. Parapsychology persisted for a time at Imperial University in Japan, with publications such as ''Clairvoyance and Thoughtography'' by Tomokichi Fukurai, but it was mostly shunned by 1913. As a discipline, psychology has long sought to fend off accusations that it is a "soft" science. Philosopher of science

Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American philosopher of science whose 1962 book '' The Structure of Scientific Revolutions'' was influential in both academic and popular circles, introducing the term ''paradig ...

's 1962 critique implied psychology overall was in a pre-paradigm state, lacking agreement on the type of overarching theory found in mature sciences such as chemistry and physics. Because some areas of psychology rely on research methods such as surveys and questionnaires, critics asserted that psychology is not an objective science. Skeptics have suggested that personality, thinking, and emotion cannot be directly measured and are often inferred from subjective self-reports, which may be problematic. Experimental psychologists have devised a variety of ways to indirectly measure these elusive phenomenological entities.Peterson, C. (23 May 2009)
"Subjective and objective research in positive psychology: A biological characteristic is linked to well-being"
. ''Psychology Today''. Retrieved 20 April 2010. Panksepp, J. (1998)
''Affective neuroscience: The foundations of human and animal emotions''
. New York: Oxford University Press, p. 9. Divisions still exist within the field, with some psychologists more oriented towards the unique experiences of individual humans, which cannot be understood only as data points within a larger population. Critics inside and outside the field have argued that mainstream psychology has become increasingly dominated by a "cult of empiricism," which limits the scope of research because investigators restrict themselves to methods derived from the physical sciences. Feminist critiques have argued that claims to scientific objectivity obscure the values and agenda of (historically) mostly male researchers. Jean Grimshaw, for example, argues that mainstream psychological research has advanced a patriarchal agenda through its efforts to control behavior.

Major schools of thought

Biological

Simulated Connectivity Damage of Phineas Gage 4 vanHorn PathwaysDamaged

Psychologists generally consider biology the substrate of thought and feeling, and therefore an important area of study. Behaviorial neuroscience, also known as biological psychology, involves the application of biological principles to the study of physiological and genetic mechanisms underlying behavior in humans and other animals. The allied field of comparative psychology is the scientific study of the behavior and mental processes of non-human animals. A leading question in behavioral neuroscience has been whether and how mental functions are localized in the brain. From Phineas Gage to H.M. and Clive Wearing, individual people with mental deficits traceable to physical brain damage have inspired new discoveries in this area.Richard F. Thompson & Stuart M. Zola, "Biological Psychology", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 1: ''History of Psychology''. Modern behavioral neuroscience could be said to originate in the 1870s, when in France

Paul Broca Pierre Paul Broca (, also , , ; 28 June 1824 – 9 July 1880) was a French physician, anatomist and anthropologist. He is best known for his research on Broca's area, a region of the frontal lobe that is named after him. Broca's area is involve ...

traced production of speech to the left frontal gyrus, thereby also demonstrating hemispheric lateralization of brain function. Soon after,

Carl Wernicke Carl (or Karl) Wernicke (; ; 15 May 1848 – 15 June 1905) was a German physician, anatomist, psychiatrist and neuropathologist. He is known for his influential research into the pathological effects of specific forms of encephalopathy and also ...

identified a related area necessary for the understanding of speech. The contemporary field of behavioral neuroscience focuses on the physical basis of behavior. Behaviorial neuroscientists use animal models, often relying on rats, to study the neural, genetic, and cellular mechanisms that underlie behaviors involved in learning, memory, and fear responses. Cognitive neuroscientists, by using neural imaging tools, investigate the neural correlates of psychological processes in humans. Neuropsychologists conduct psychological assessments to determine how an individual's behavior and cognition are related to the brain. The biopsychosocial model is a cross-disciplinary, holistic model that concerns the ways in which interrelationships of biological, psychological, and socio-environmental factors affect health and behavior.

Evolutionary psychology Evolutionary psychology is a theoretical approach in psychology that examines cognition and behavior from a modern evolutionary perspective. It seeks to identify human psychological adaptations with regards to the ancestral problems they evol ...

approaches thought and behavior from a modern

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

ary perspective. This perspective suggests that psychological adaptations evolved to solve recurrent problems in human ancestral environments. Evolutionary psychologists attempt to find out how human psychological traits are evolved adaptations, the results of

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Cha ...

sexual selection Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ( ...

over the course of human evolution. The history of the biological foundations of psychology includes evidence of racism. The idea of white supremacy and indeed the modern concept of race itself arose during the process of world conquest by Europeans. Carl von Linnaeus's four-fold classification of humans classifies Europeans as intelligent and severe, Americans as contented and free, Asians as ritualistic, and Africans as lazy and capricious. Race was also used to justify the construction of socially specific mental disorders such as ''

drapetomania Drapetomania was a supposed mental illness that, in 1851, American physician Samuel A. Cartwright hypothesized as the cause of enslaved Africans fleeing captivity. This hypothesis centered around the belief that slavery was such an improvement u ...

'' and ''

dysaesthesia aethiopica In psychiatry, dysaesthesia aethiopica ("Black (Ethiopian) bad feeling) was an alleged mental illness described by American physician Samuel A. Cartwright in 1851, which proposed a theory for the cause of laziness among slaves. Today, ''dysaesthe ...

''—the behavior of uncooperative African slaves. After the creation of experimental psychology, "ethnical psychology" emerged as a subdiscipline, based on the assumption that studying primitive races would provide an important link between animal behavior and the psychology of more evolved humans.

Behaviorist

A tenet of behavioral research is that a large part of both human and lower-animal behavior is learned. A principle associated with behavioral research is that the mechanisms involved in learning apply to humans and non-human animals. Behavioral researchers have developed a treatment known as

behavior modification Behavior modification is an early approach that used respondent and operant conditioning to change behavior. Based on methodological behaviorism, overt behavior was modified with consequences, including positive and negative reinforcement conti ...

, which is used to help individuals replace undesirable behaviors with desirable ones. Early behavioral researchers studied stimulus–response pairings, now known as

. They demonstrated that when a biologically potent stimulus (e.g., food that elicits salivation) is paired with a previously neutral stimulus (e.g., a bell) over several learning trials, the neutral stimulus by itself can come to elicit the response the biologically potent stimulus elicits.

—known best for inducing dogs to salivate in the presence of a stimulus previously linked with food—became a leading figure in the Soviet Union and inspired followers to use his methods on humans. In the United States, Edward Lee Thorndike initiated "

connectionist Connectionism refers to both an approach in the field of cognitive science that hopes to explain mental phenomena using artificial neural networks (ANN) and to a wide range of techniques and algorithms using ANNs in the context of artificial int ...

" studies by trapping animals in "puzzle boxes" and rewarding them for escaping. Thorndike wrote in 1911, "There can be no moral warrant for studying man's nature unless the study will enable us to control his acts." From 1910 to 1913 the American Psychological Association went through a sea change of opinion, away from

mentalism Mentalism is a performing art in which its practitioners, known as mentalists, appear to demonstrate highly developed mental or intuitive abilities. Performances may appear to include hypnosis, telepathy, clairvoyance, divination, precognitio ...

and towards "behavioralism." In 1913, John B. Watson coined the term behaviorism for this school of thought. Watson's famous

Little Albert experiment The Little Albert experiment was a controlled experiment showing empirical evidence of classical conditioning in humans. The study also provides an example of stimulus generalization. It was carried out by John B. Watson and his Doctoral studen ...

in 1920 was at first thought to demonstrate that repeated use of upsetting loud noises could instill phobias (aversions to other stimuli) in an infant human, although such a conclusion was likely an exaggeration.

Karl Lashley Karl Spencer Lashley (June 7, 1890 – August 7, 1958) was a psychologist and behaviorist remembered for his contributions to the study of learning and memory. A ''Review of General Psychology'' survey, published in 2002, ranked Lashley as the 61 ...

, a close collaborator with Watson, examined biological manifestations of learning in the brain.

Clark L. Hull Clark Leonard Hull (May 24, 1884 – May 10, 1952) was an American psychologist who sought to explain learning and motivation by scientific laws of behavior. Hull is known for his debates with Edward C. Tolman. He is also known for his work in d ...

, Edwin Guthrie, and others did much to help behaviorism become a widely used paradigm. A new method of "instrumental" or " operant" conditioning added the concepts of

reinforcement In behavioral psychology, reinforcement is a consequence applied that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus. This strengthening effect may be measured as a higher fr ...

and punishment to the model of behavior change. Radical behaviorists avoided discussing the inner workings of the mind, especially the unconscious mind, which they considered impossible to assess scientifically. Operant conditioning was first described by Miller and Kanorski and popularized in the U.S. by B.F. Skinner, who emerged as a leading intellectual of the behaviorist movement.

Noam Chomsky Avram Noam Chomsky (born December 7, 1928) is an American public intellectual: a linguist, philosopher, cognitive scientist, historian, social critic, and political activist. Sometimes called "the father of modern linguistics", Chomsky i ...

published an influential critique of radical behaviorism on the grounds that behaviorist principles could not adequately explain the complex mental process of language acquisition and language use. The review, which was scathing, did much to reduce the status of behaviorism within psychology. Martin Seligman and his colleagues discovered that they could condition in dogs a state of "

learned helplessness Learned helplessness is the behavior exhibited by a subject after enduring repeated aversive stimuli beyond their control. It was initially thought to be caused by the subject's acceptance of their powerlessness, by way of their discontinuing atte ...

", which was not predicted by the behaviorist approach to psychology.

Edward C. Tolman Edward Chace Tolman (April 14, 1886 – November 19, 1959) was an American psychologist and a professor of psychology at the University of California, Berkeley. Through Tolman's theories and works, he founded what is now a branch of psychology know ...

advanced a hybrid "cognitive behavioral" model, most notably with his 1948 publication discussing the

cognitive map A cognitive map is a type of mental representation which serves an individual to acquire, code, store, recall, and decode information about the relative locations and attributes of phenomena in their everyday or metaphorical spatial environment. T ...

s used by rats to guess at the location of food at the end of a maze. Skinner's behaviorism did not die, in part because it generated successful practical applications. The Association for Behavior Analysis International was founded in 1974 and by 2003 had members from 42 countries. The field has gained a foothold in Latin America and Japan.

Applied behavior analysis Applied behavior analysis (ABA), also called behavioral engineering, is a psychological intervention that applies empirical approaches based upon the principles of respondent and operant conditioning to change behavior of social significanc ...

is the term used for the application of the principles of operant conditioning to change socially significant behavior (it supersedes the term, "behavior modification").

Cognitive

Green Red Blue
Purple Blue Purple ---- Blue Purple Red
Green Purple Green ---- The Stroop effect is the fact that naming the color of the first set of words is easier and quicker than the second.

Cognitive psychology involves the study of

mental process Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...

es, including

, attention, language comprehension and production,

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

, and problem solving. Researchers in the field of cognitive psychology are sometimes called cognitivists. They rely on an information processing model of mental functioning. Cognitivist research is informed by functionalism and experimental psychology. Working memory model

Starting in the 1950s, the experimental techniques developed by Wundt, James, Ebbinghaus, and others re-emerged as experimental psychology became increasingly cognitivist and, eventually, constituted a part of the wider, interdisciplinary cognitive science. Some called this development the

cognitive revolution The cognitive revolution was an intellectual movement that began in the 1950s as an interdisciplinary study of the mind and its processes. It later became known collectively as cognitive science. The relevant areas of interchange were between th ...

because it rejected the anti-mentalist dogma of behaviorism as well as the strictures of psychoanalysis.Mandler, G. (2007). A history of modern experimental psychology: From James and Wundt to cognitive science. Cambridge, MA: MIT Press.

Albert Bandura Albert Bandura (; December 4, 1925 – July 26, 2021) was a Canadian-American psychologist who was the David Starr Jordan Professor in Psychology at Stanford University. Bandura was responsible for contributions to the field of education and to ...

helped along the transition in psychology from behaviorism to cognitive psychology. Bandura and other social learning theorists advanced the idea of vicarious learning. In other words, they advanced the view that a child can learn by observing his or her social environment and not necessarily from having been reinforced for enacting a behavior, although they did not rule out the influence of reinforcement on learning a behavior. Müller-Lyer illusion

Technological advances also renewed interest in mental states and mental representations. English neuroscientist

Charles Sherrington Sir Charles Scott Sherrington (27 November 1857 – 4 March 1952) was an eminent English neurophysiologist. His experimental research established many aspects of contemporary neuroscience, including the concept of the spinal reflex as a system ...

and Canadian psychologist

Donald O. Hebb Donald Olding Hebb (July 22, 1904 – August 20, 1985) was a Canadian psychologist who was influential in the area of neuropsychology, where he sought to understand how the function of neurons contributed to psychological processes such as l ...

used experimental methods to link psychological phenomena to the structure and function of the brain. The rise of computer science, cybernetics, and artificial intelligence underlined the value of comparing information processing in humans and machines. A popular and representative topic in this area is cognitive bias, or irrational thought. Psychologists (and economists) have classified and described a sizeable catalogue of biases which recur frequently in human thought. The

availability heuristic The availability heuristic, also known as availability bias, is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. This heuristic, operating on the ...

, for example, is the tendency to overestimate the importance of something which happens to come readily to mind. Elements of behaviorism and cognitive psychology were synthesized to form cognitive behavioral therapy, a form of psychotherapy modified from techniques developed by American psychologist

Albert Ellis Albert Ellis (September 27, 1913 – July 24, 2007) was an American psychologist and psychotherapist who founded rational emotive behavior therapy (REBT). He held MA and PhD degrees in clinical psychology from Columbia University, and was certi ...

and American psychiatrist

Aaron T. Beck Aaron Temkin Beck (July 18, 1921 – November 1, 2021) was an American psychiatrist who was a professor in the department of psychiatry at the University of Pennsylvania.

. On a broader level, cognitive science is an interdisciplinary enterprise involving cognitive psychologists, cognitive neuroscientists, linguists, and researchers in artificial intelligence, human–computer interaction, and

computational neuroscience Computational neuroscience (also known as theoretical neuroscience or mathematical neuroscience) is a branch of neuroscience which employs mathematical models, computer simulations, theoretical analysis and abstractions of the brain to u ...

. The discipline of cognitive science covers cognitive psychology as well as philosophy of mind, computer science, and neuroscience. Computer simulations are sometimes used to model phenomena of interest.

Social

Social psychology is concerned with how behaviors, thoughts, feelings, and the social environment influence human interactions. Social psychologists study such topics as the influence of others on an individual's behavior (e.g. conformity, persuasion) and the formation of beliefs, attitudes, and stereotypes about other people.

Social cognition Social cognition is a sub-topic of various branches of psychology that focuses on how people process, store, and apply information about other people and social situations. It focuses on the role that cognitive processes play in social interacti ...

fuses elements of social and cognitive psychology for the purpose of understanding how people process, remember, or distort social information. The study of

group dynamics Group dynamics is a system of behaviors and psychological processes occurring within a social group (''intra''group dynamics), or between social groups ( ''inter''group dynamics). The study of group dynamics can be useful in understanding decision- ...

involves research on the nature of leadership, organizational communication, and related phenomena. In recent years, social psychologists have become interested in implicit measures, mediational models, and the interaction of person and social factors in accounting for behavior. Some concepts that sociologists have applied to the study of psychiatric disorders, concepts such as the social role, sick role, social class, life events, culture, migration, and

total institution A total institution is a place of work and residence where a great number of similarly situated people, cut off from the wider community for a considerable time, together lead an enclosed, formally administered round of life. Privacy is limited in ...

, have influenced social psychologists.

Psychoanalytic

Psychoanalysis refers to the theories and therapeutic techniques applied to the unconscious mind and its impact on everyday life. These theories and techniques inform treatments for mental disorders. Psychoanalysis originated in the 1890s, most prominently with the work of

Sigmund Freud Sigmund Freud ( , ; born Sigismund Schlomo Freud; 6 May 1856 – 23 September 1939) was an Austrian neurologist and the founder of psychoanalysis, a clinical method for evaluating and treating pathologies explained as originating in conflicts ...

. Freud's psychoanalytic theory was largely based on interpretive methods,

, and clinical observation. It became very well known, largely because it tackled subjects such as sexuality, repression, and the unconscious. Freud pioneered the methods of free association and

dream interpretation Dream interpretation is the process of assigning meaning to dreams. Although associated with some forms of psychotherapy, there is no reliable evidence that understanding or interpreting dreams has a positive impact on one's mental health. In m ...

. Psychoanalytic theory is not monolithic. Other well-known psychoanalytic thinkers who diverged from Freud include

Alfred Adler Alfred Adler ( , ; 7 February 1870 – 28 May 1937) was an Austrian medical doctor, psychotherapist, and founder of the school of individual psychology. His emphasis on the importance of feelings of belonging, family constellation and birth orde ...

Carl Jung Carl Gustav Jung ( ; ; 26 July 1875 – 6 June 1961) was a Swiss psychiatrist and psychoanalyst who founded analytical psychology. Jung's work has been influential in the fields of psychiatry, anthropology, archaeology, literature, phi ...

, Erik Erikson,

Melanie Klein Melanie Klein (née Reizes; 30 March 1882 – 22 September 1960) was an Austrian-British author and psychoanalyst known for her work in child analysis. She was the primary figure in the development of object relations theory. Klein suggested t ...

, D.W. Winnicott, Karen Horney, Erich Fromm,

John Bowlby Edward John Mostyn Bowlby, CBE, FBA, FRCP, FRCPsych (; 26 February 1907 – 2 September 1990) was a British psychologist, psychiatrist, and psychoanalyst, notable for his interest in child development and for his pioneering work in attach ...

, Freud's daughter

Anna Freud Anna Freud (3 December 1895 – 9 October 1982) was a British psychoanalyst of Austrian-Jewish descent. She was born in Vienna, the sixth and youngest child of Sigmund Freud and Martha Bernays. She followed the path of her father and contribut ...

, and

Harry Stack Sullivan Herbert "Harry" Stack Sullivan (February 21, 1892, Norwich, New York – January 14, 1949, Paris, France) was an American Neo-Freudian psychiatrist and psychoanalyst who held that "personality can never be isolated from the complex interpersonal r ...

. These individuals ensured that psychoanalysis would evolve into diverse schools of thought. Among these schools are

ego psychology Ego psychology is a school of psychoanalysis rooted in Sigmund Freud's structural id-ego-superego model of the mind. An individual interacts with the external world as well as responds to internal forces. Many psychoanalysts use a theoretical c ...

object relations Object relations theory is a school of thought in psychoanalytic theory centered around theories of stages of ego development. Its concerns include the relation of the psyche to others in childhood and the exploration of relationships between ...

, and interpersonal, Lacanian, and

relational psychoanalysis Relational psychoanalysis is a school of psychoanalysis in the United States that emphasizes the role of real and imagined relationships with others in mental disorder and psychotherapy. 'Relational psychoanalysis is a relatively new and evolving ...

. Psychologists such as Hans Eysenck and philosophers including Karl Popper sharply criticized psychoanalysis. Popper argued that psychoanalysis had been misrepresented as a scientific discipline,Karl Popper, Conjectures and Refutations, London: Routledge and Keagan Paul, 1963, pp. 33–39; from Theodore Schick, ed., Readings in the Philosophy of Science, Mountain View, CA: Mayfield Publishing Company, 2000, pp. 9–13
Faculty.washington.edu
whereas Eysenck advanced the view that psychoanalytic tenets had been contradicted by

al data. By the end of the 20th century, psychology departments in American universities mostly had marginalized Freudian theory, dismissing it as a "desiccated and dead" historical artifact. Researchers such as António Damásio,

Oliver Sacks Oliver Wolf Sacks, (9 July 1933 – 30 August 2015) was a British neurologist, naturalist, historian of science, and writer. Born in Britain, Sacks received his medical degree in 1958 from The Queen's College, Oxford, before moving to the Uni ...

, and Joseph LeDoux; and individuals in the emerging field of neuro-psychoanalysis have defended some of Freud's ideas on scientific grounds.

Existential-humanistic

Humanistic psychology Humanistic psychology is a psychological perspective that arose in the mid-20th century in answer to two theories: Sigmund Freud's psychoanalytic theory and B. F. Skinner's behaviorism. Thus, Abraham Maslow established the need for a "third force ...

, which has been influenced by existentialism and phenomenology, stresses

free will Free will is the capacity of agents to choose between different possible courses of action unimpeded. Free will is closely linked to the concepts of moral responsibility, praise, culpability, sin, and other judgements which apply only to ac ...

and self-actualization.Oxford University Press. (2015). ''A Dictionary of Psychology, 4th ed.'' Edited by Andrew M. Colman. Oxford Reference Online. Oxford: Author. It emerged in the 1950s as a movement within academic psychology, in reaction to both behaviorism and psychoanalysis. The humanistic approach seeks to view the whole person, not just fragmented parts of the personality or isolated cognitions. Humanistic psychology also focuses on personal growth,

self-identity In the psychology of self, one's self-concept (also called self-construction, self-identity, self-perspective or self-structure) is a collection of beliefs about oneself. Generally, self-concept embodies the answer to the question ''"Who am I? ...

, death, aloneness, and freedom. It emphasizes subjective meaning, the rejection of determinism, and concern for positive growth rather than pathology. Some founders of the humanistic school of thought were American psychologists Abraham Maslow, who formulated a hierarchy of human needs, and

Carl Rogers Carl Ransom Rogers (January 8, 1902 – February 4, 1987) was an American psychologist and among the founders of the humanistic approach (and client-centered approach) in psychology. Rogers is widely considered one of the founding fathers of ps ...

, who created and developed client-centered therapy. Later, positive psychology opened up humanistic themes to scientific study. Positive psychology is the study of factors which contribute to human happiness and well-being, focusing more on people who are currently healthy. In 2010, ''Clinical Psychological Review'' published a special issue devoted to positive psychological interventions, such as gratitude journaling and the physical expression of gratitude. It is, however, far from clear that positive psychology is effective in making people happier.Ehrenreich, B. (2009). ''Bright-sided: How the relentless promotion of positive thinking has undermined America''. New York: Henry Holt. Singal, J. (2021, June 7). Positive psychology goes to war: How the Army adopted an untested, evidence-free approach to fighting PTSD. ''Chronicle of Higher Education''. Positive psychological interventions have been limited in scope, but their effects are thought to be somewhat better than

placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can af ...

effects. The ''American Association for Humanistic Psychology'', formed in 1963, declared: Existential psychology emphasizes the need to understand a client's total orientation towards the world. Existential psychology is opposed to reductionism, behaviorism, and other methods that objectify the individual. In the 1950s and 1960s, influenced by philosophers Søren Kierkegaard and

Martin Heidegger Martin Heidegger (; ; 26 September 188926 May 1976) was a German philosopher who is best known for contributions to phenomenology, hermeneutics, and existentialism. He is among the most important and influential philosophers of the 20th ce ...

, psychoanalytically trained American psychologist

Rollo May Rollo Reece May (April 21, 1909 – October 22, 1994) was an American existential psychologist and author of the influential book '' Love and Will'' (1969). He is often associated with humanistic psychology and existentialist philosophy, ...

helped to develop existential psychology.

Existential psychotherapy Existential psychotherapy is a form of psychotherapy based on the model of human nature and experience developed by the existential tradition of European philosophy. It focuses on concepts that are universally applicable to human existence inclu ...

, which follows from existential psychology, is a therapeutic approach that is based on the idea that a person's inner conflict arises from that individual's confrontation with the givens of existence. Swiss psychoanalyst

Ludwig Binswanger Ludwig Binswanger (; ; 13 April 1881 – 5 February 1966) was a Swiss psychiatrist and pioneer in the field of existential psychology. His parents were Robert Johann Binswanger (1850–1910) and Bertha Hasenclever (1847–1896). Robert's Ger ...

and American psychologist George Kelly may also be said to belong to the existential school. Existential psychologists tend to differ from more "humanistic" psychologists in the former's relatively neutral view of human nature and relatively positive assessment of anxiety. Existential psychologists emphasized the humanistic themes of death, free will, and meaning, suggesting that meaning can be shaped by myths and narratives; meaning can be deepened by the acceptance of free will, which is requisite to living an

authentic Authenticity or authentic may refer to: * Authentication, the act of confirming the truth of an attribute Arts and entertainment * Authenticity in art, ways in which a work of art or an artistic performance may be considered authentic Music * A ...

life, albeit often with anxiety with regard to death. Austrian existential psychiatrist and

Holocaust The Holocaust, also known as the Shoah, was the genocide of European Jews during World War II. Between 1941 and 1945, Nazi Germany and its collaborators systematically murdered some six million Jews across German-occupied Europe; ...

survivor Viktor Frankl drew evidence of meaning's therapeutic power from reflections upon his own internment. He created a variation of existential psychotherapy called logotherapy, a type of

existentialist Existentialism ( ) is a form of philosophical inquiry that explores the problem of human existence and centers on human thinking, feeling, and acting. Existentialist thinkers frequently explore issues related to the meaning, purpose, and value ...

analysis that focuses on a ''will to meaning'' (in one's life), as opposed to Adler's

Nietzsche Friedrich Wilhelm Nietzsche (; or ; 15 October 1844 – 25 August 1900) was a German philosopher, prose poet, cultural critic, philologist, and composer whose work has exerted a profound influence on contemporary philosophy. He began his car ...

an doctrine of ''

will to power The will to power (german: der Wille zur Macht) is a concept in the philosophy of Friedrich Nietzsche. The will to power describes what Nietzsche may have believed to be the main driving force in humans. However, the concept was never systemati ...

'' or Freud's '' will to pleasure''.

Themes

Personality

Personality psychology is concerned with enduring patterns of behavior, thought, and emotion. Theories of personality vary across different psychological schools of thought. Each theory carries different assumptions about such features as the role of the unconscious and the importance of childhood experience. According to Freud, personality is based on the dynamic interactions of the

id, ego, and super-ego The id, ego, and super-ego are a set of three concepts in psychoanalytic theory describing distinct, interacting agents in the psychic apparatus (defined in Sigmund Freud's structural model of the psyche). The three agents are theoretical con ...

. By contrast, trait theorists have developed taxonomies of personality constructs in describing personality in terms of key traits. Trait theorists have often employed statistical data-reduction methods, such as

factor analysis Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved variables called factors. For example, it is possible that variations in six observed ...

. Although the number of proposed traits has varied widely, Hans Eysenck's early biologically-based model suggests at least three major trait constructs are necessary to describe human personality, extraversion–introversion, neuroticism-stability, and

psychoticism Psychoticism is one of the three traits used by the psychologist Hans Eysenck in his P–E–N model ( psychoticism, extraversion and neuroticism) model of personality. Nature Psychoticism is conceptually similar to the ''constraint'' factor ...

-normality.

Raymond Cattell Raymond Bernard Cattell (20 March 1905 – 2 February 1998) was a British-American psychologist, known for his psychometric research into intrapersonal psychological structure.Gillis, J. (2014). ''Psychology's Secret Genius: The Lives and Works ...

empirically derived a theory of

16 personality factors The Sixteen Personality Factor Questionnaire (16PF) is a self-report personality test developed over several decades of empirical research by Raymond B. Cattell, Maurice Tatsuoka and Herbert Eber. The 16PF provides a measure of personality and c ...

at the primary-factor level and up to eight broader second-stratum factors. Since the 1980s, the Big Five (

openness to experience Openness to experience is one of the domains which are used to describe human personality in the Five Factor Model. Openness involves six facets, or dimensions: active imagination (fantasy), aesthetic sensitivity, attentiveness to inner feelings ...

conscientiousness Conscientiousness is the personality trait of being careful, or diligent. Conscientiousness implies a desire to do a task well, and to take obligations to others seriously. Conscientious people tend to be efficient and organized as opposed to ...

, extraversion,

agreeableness Agreeableness is a personality trait manifesting itself in individual behavioral characteristics that are perceived as kind, sympathetic, cooperative, warm, and considerate. In contemporary personality psychology, agreeableness is one of the fiv ...

, and neuroticism) emerged as an important trait theory of personality. Dimensional models of personality are receiving increasing support, and a version of dimensional assessment has been included in the DSM-V. However, despite a plethora of research into the various versions of the "Big Five" personality dimensions, it appears necessary to move on from static conceptualizations of personality structure to a more dynamic orientation, acknowledging that personality constructs are subject to learning and change over the lifespan. An early example of personality assessment was the

Woodworth Personal Data Sheet The Woodworth Personal Data Sheet, sometimes known as the Woodworth Psychoneurotic Inventory was a personality test, commonly cited as the first personality test, developed by Robert S. Woodworth during World War I for the United States Army. It wa ...

, constructed during World War I. The popular, although psychometrically inadequate,

Myers–Briggs Type Indicator In personality typology, the Myers–Briggs Type Indicator (MBTI) is an introspective self-report questionnaire indicating differing psychological preferences in how people perceive the world and make decisions. The test attempts to assign ...

was developed to assess individuals' "personality types" according to the personality theories of Carl Jung. The Minnesota Multiphasic Personality Inventory (MMPI), despite its name, is more a dimensional measure of psychopathology than a personality measure.

California Psychological Inventory The California Psychological Inventory (CPI) is a self-report inventory created by Harrison G. Gough and currently published by Consulting Psychologists Press. The text containing the test was first published in 1956, and the most recent revision w ...

contains 20 personality scales (e.g., independence, tolerance). The

International Personality Item Pool The International Personality Item Pool (IPIP) is a public domain collection of items for use in personality tests. It is managed by the Oregon Research Institute. The pool contains 3,329 items. These items make up more than 250 inventories that m ...

, which is in the public domain, has become a source of scales that can be used personality assessment.

Unconscious mind

Study of the unconscious mind, a part of the psyche outside the individual's awareness but that is believed to influence conscious thought and behavior, was a hallmark of early psychology. In one of the first psychology experiments conducted in the United States, C.S. Peirce and

Joseph Jastrow Joseph Jastrow (January 30, 1863 – January 8, 1944) was a Polish-born American psychologist, noted for inventions in experimental psychology, design of experiments, and psychophysics. He also worked on the phenomena of optical illusions, ...

found in 1884 that research subjects could choose the minutely heavier of two weights even if consciously uncertain of the difference. Freud popularized the concept of the unconscious mind, particularly when he referred to an uncensored intrusion of unconscious thought into one's speech (a

Freudian slip In psychoanalysis, a Freudian slip, also called parapraxis, is an error in speech, memory, or physical action that occurs due to the interference of an unconscious subdued wish or internal train of thought. Classical examples involve slips of ...

) or to his efforts to interpret dreams. His 1901 book ''

The Psychopathology of Everyday Life ''Psychopathology of Everyday Life'' (german: Zur Psychopathologie des Alltagslebens) is a 1901 work by Sigmund Freud, the founder of psychoanalysis. Based on Freud's researches into slips and parapraxes from 1897 onwards, it became perhaps the ...

'' catalogues hundreds of everyday events that Freud explains in terms of unconscious influence. Pierre Janet advanced the idea of a subconscious mind, which could contain autonomous mental elements unavailable to the direct scrutiny of the subject.John F. Kihlstrom,
The Psychological Unconscious
", in Lawrence Pervin & Oliver John (eds.), ''Handbook of Personality''; New York: Guilford Press, 1999. Also se

. The concept of unconscious processes has remained important in psychology. Cognitive psychologists have used a "filter" model of attention. According to the model, much information processing takes place below the threshold of consciousness, and only certain stimuli, limited by their nature and number, make their way through the filter. Much research has shown that subconscious ''

priming Priming may refer to: * Priming (agriculture), a form of seed planting preparation, in which seeds are soaked before planting * Priming (immunology), a process occurring when a specific antigen is presented to naive lymphocytes causing them to d ...

'' of certain ideas can covertly influence thoughts and behavior. Because of the unreliability of self-reporting, a major hurdle in this type of research involves demonstrating that a subject's conscious mind has not perceived a target stimulus. For this reason, some psychologists prefer to distinguish between '' implicit'' and '' explicit'' memory. In another approach, one can also describe a subliminal stimulus as meeting an ''objective'' but not a ''subjective'' threshold.William P. Banks & Ilya Farber, "Consciousness", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 4: ''Experimental Psychology''. The

model of John Bargh and others involves the ideas of automaticity and unconscious processing in our understanding of

, Also see: John A. Bargh, "The Automaticity of Everyday Life", in Robert S. Wyer Jr. (ed.), ''The Automaticity of Everyday Life'', Advances in Social Cognition, Volume X; Mahwah, NJ: Lawrence Erlbaum Associates, 1997; John F. Kihlstrom,
The Automaticity Juggernaut—or, Are We Automatons After All?
", in John Baer, James C. Kaufmna, & Roy F. Baumeister (eds.), ''Are We Free? Psychology and Free Will''; Oxford University Press, 2008. although there has been dispute with regard to replication.S. Doyen, O. Klein, C. L. Pichon and A. Cleeremans. (2012). Behavioral priming: it's all in the mind, but whose mind? ''PLoS One'', 7
e29081
Some experimental data suggest that the brain begins to consider taking actions before the mind becomes aware of them. The influence of unconscious forces on people's choices bears on the philosophical question of free will. John Bargh, Daniel Wegner, and

Ellen Langer Ellen Jane Langer (; born March 25, 1947) is an American professor of psychology at Harvard University; in 1981, she became the first woman ever to be tenured in psychology at Harvard. Langer studies the illusion of control, decision-making, agi ...

describe free will as an illusion.

Motivation

Some psychologists study motivation or the subject of why people or lower animals initiate a behavior at a particular time. It also involves the study of why humans and lower animals continue or terminate a behavior. Psychologists such as William James initially used the term ''motivation'' to refer to intention, in a sense similar to the concept of '' will'' in European philosophy. With the steady rise of Darwinian and Freudian thinking, instinct also came to be seen as a primary source of motivation.Forgas, Williams, & Laham, "Social Motivation: Introduction and Overview", in Forgas, Williams, & Laham, ''Social Motivation'' (2005). According to

drive theory In psychology, a drive theory, theory of drives or drive doctrine is a theory that attempts to analyze, classify or define the psychological drives. A drive is an instinctual need that has the power of driving the behavior of an individual; an " ...

, the forces of instinct combine into a single source of energy which exerts a constant influence. Psychoanalysis, like biology, regarded these forces as demands originating in the nervous system. Psychoanalysts believed that these forces, especially the sexual instincts, could become entangled and transmuted within the psyche. Classical psychoanalysis conceives of a struggle between the pleasure principle and the reality principle, roughly corresponding to id and ego. Later, in '' Beyond the Pleasure Principle'', Freud introduced the concept of the '' death drive'', a compulsion towards aggression, destruction, and psychic repetition of traumatic events. Meanwhile, behaviorist researchers used simple dichotomous models (pleasure/pain, reward/punishment) and well-established principles such as the idea that a thirsty creature will take pleasure in drinking.Bill P. Godsil, Matthew R. Tinsley, & Michael S. Fanselow, "Motivation", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 4: ''Experimental Psychology''. Clark Hull formalized the latter idea with his drive reduction model. Hunger, thirst, fear, sexual desire, and thermoregulation constitute fundamental motivations in animals. Humans seem to exhibit a more complex set of motivations—though theoretically these could be explained as resulting from desires for belonging, positive self-image, self-consistency, truth, love, and control. Motivation can be modulated or manipulated in many different ways. Researchers have found that

eating Eating (also known as consuming) is the ingestion of food, typically to provide a heterotrophic organism with energy and to allow for growth. Animals and other heterotrophs must eat in order to survive — carnivores eat other animals, he ...

, for example, depends not only on the organism's fundamental need for

homeostasis In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and ...

—an important factor causing the experience of hunger—but also on circadian rhythms, food availability, food palatability, and cost. Abstract motivations are also malleable, as evidenced by such phenomena as ''goal contagion'': the adoption of goals, sometimes unconsciously, based on inferences about the goals of others. Vohs and Baumeister suggest that contrary to the need-desire-fulfilment cycle of animal instincts, human motivations sometimes obey a "getting begets wanting" rule: the more you get a reward such as self-esteem, love, drugs, or money, the more you want it. They suggest that this principle can even apply to food, drink, sex, and sleep.

Development psychology

Developmental psychology refers to the scientific study of how and why the thought processes, emotions, and behaviors of humans change over the course of their lives. Some credit Charles Darwin with conducting the first systematic study within the rubric of developmental psychology, having published in 1877 a short paper detailing the development of innate forms of communication based on his observations of his infant son. The main origins of the discipline, however, are found in the work of

Jean Piaget Jean William Fritz Piaget (, , ; 9 August 1896 – 16 September 1980) was a Swiss psychologist known for his work on child development. Piaget's theory of cognitive development and epistemological view are together called "genetic epistemolo ...

. Like Piaget, developmental psychologists originally focused primarily on the development of cognition from infancy to adolescence. Later, developmental psychology extended itself to the study cognition over the life span. In addition to studying cognition, developmental psychologists have also come to focus on affective, behavioral, moral, social, and neural development. Developmental psychologists who study children use a number of research methods. For example, they make observations of children in natural settings such as preschools and engage them in experimental tasks. Such tasks often resemble specially designed games and activities that are both enjoyable for the child and scientifically useful. Developmental researchers have even devised clever methods to study the mental processes of infants. In addition to studying children, developmental psychologists also study aging and processes throughout the life span, including old age. These psychologists draw on the full range of psychological theories to inform their research.Crain, W. (2014). ''Theories of development: Concepts and applications. 6th ed.'' Edinburgh: Pearson.

Genes and environment

All researched psychological traits are influenced by both genes and environment, to varying degrees. These two sources of influence are often confounded in observational research of individuals and families. An example of this confounding can be shown in the transmission of depression from a depressed mother to her offspring. A theory based on environmental transmission would hold that an offspring, by virtue of his or her having a problematic rearing environment managed by a depressed mother, is at risk for developing depression. On the other hand, a hereditarian theory would hold that depression risk in an offspring is influenced to some extent by genes passed to the child from the mother. Genes and environment in these simple transmission models are completely confounded. A depressed mother may both carry genes that contribute to depression in her offspring and also create a rearing environment that increases the risk of depression in her child.

Behavioral genetics Behavioural genetics, also referred to as behaviour genetics, is a field of scientific research that uses genetic methods to investigate the nature and origins of individual differences in behaviour. While the name "behavioural genetics" c ...

researchers have employed methodologies that help to disentangle this confound and understand the nature and origins of individual differences in behavior. Traditionally the research has involved

twin studies Twin studies are studies conducted on identical or fraternal twins. They aim to reveal the importance of environmental and genetic influences for traits, phenotypes, and disorders. Twin research is considered a key tool in behavioral genetics ...

and adoption studies, two designs where genetic and environmental influences can be partially un-confounded. More recently, gene-focused research has contributed to understanding genetic contributions to the development of psychological traits. The availability of microarray molecular genetic or

genome sequencing Whole genome sequencing (WGS), also known as full genome sequencing, complete genome sequencing, or entire genome sequencing, is the process of determining the entirety, or nearly the entirety, of the DNA sequence of an organism's genome at a ...

technologies allows researchers to measure participant DNA variation directly, and test whether individual genetic variants within genes are associated with psychological traits and psychopathology through methods including

genome-wide association studies In genomics, a genome-wide association study (GWA study, or GWAS), also known as whole genome association study (WGA study, or WGAS), is an observational study of a genome-wide set of genetic variants in different individuals to see if any varian ...

. One goal of such research is similar to that in

positional cloning A genetic screen or mutagenesis screen is an experimental technique used to identify and select individuals who possess a phenotype of interest in a mutagenized population. Hence a genetic screen is a type of phenotypic screen. Genetic screens c ...

and its success in Huntington's: once a causal gene is discovered biological research can be conducted to understand how that gene influences the phenotype. One major result of genetic association studies is the general finding that psychological traits and psychopathology, as well as complex medical diseases, are highly

polygenic A polygene is a member of a group of non- epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance), a type of ...

, where a large number (on the order of hundreds to thousands) of genetic variants, each of small effect, contribute to individual differences in the behavioral trait or propensity to the disorder. Active research continues to work toward understanding the genetic and environmental bases of behavior and their interaction.

Applications

Psychology encompasses many subfields and includes different approaches to the study of mental processes and behavior.

Psychological testing

Psychological testing has ancient origins, dating as far back as 2200 BC, in the examinations for the Chinese civil service. Written exams began during the Han dynasty (202 BC – AD 200). By 1370, the Chinese system required a stratified series of tests, involving essay writing and knowledge of diverse topics. The system was ended in 1906. In Europe, mental assessment took a different approach, with theories of

physiognomy Physiognomy (from the Greek , , meaning "nature", and , meaning "judge" or "interpreter") is the practice of assessing a person's character or personality from their outer appearance—especially the face. The term can also refer to the genera ...

—judgment of character based on the face—described by Aristotle in 4th century BC Greece. Physiognomy remained current through the Enlightenment, and added the doctrine of phrenology: a study of mind and intelligence based on simple assessment of neuroanatomy. When experimental psychology came to Britain, Francis Galton was a leading practitioner. By virtue of his procedures for measuring reaction time and sensation, he is considered an inventor of modern mental testing (also known as ''

psychometrics Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally refers to specialized fields within psychology and education devoted to testing, measurement, assessment, and ...

''). James McKeen Cattell, a student of Wundt and Galton, brought the idea of psychological testing to the United States, and in fact coined the term "mental test". In 1901, Cattell's student

Clark Wissler Clark David Wissler (September 18, 1870 – August 25, 1947) was an American anthropologist, ethnologist, and archaeologist. Early life Clark David Wissler was born in Cambridge City, Indiana on September 18, 1870 to Sylvania (née Needler) an ...

published discouraging results, suggesting that mental testing of Columbia and Barnard students failed to predict academic performance. In response to 1904 orders from the Minister of Public Instruction, French psychologists

Alfred Binet Alfred Binet (; 8 July 1857 – 18 October 1911), born Alfredo Binetti, was a French psychologist who invented the first practical IQ test, the Binet–Simon test. In 1904, the French Ministry of Education asked psychologist Alfred Binet to ...

and Théodore Simon developed and elaborated a new test of intelligence in 1905–1911. They used a range of questions diverse in their nature and difficulty. Binet and Simon introduced the concept of mental age and referred to the lowest scorers on their test as ''

idiot An idiot, in modern use, is a stupid or foolish person. 'Idiot' was formerly a technical term in legal and psychiatric contexts for some kinds of profound intellectual disability where the mental age is two years or less, and the person cannot ...

s''. Henry H. Goddard put the Binet-Simon scale to work and introduced classifications of mental level such as ''imbecile'' and ''feebleminded''. In 1916, (after Binet's death), Stanford professor Lewis M. Terman modified the Binet-Simon scale (renamed the Stanford–Binet scale) and introduced the

intelligence quotient An intelligence quotient (IQ) is a total score derived from a set of standardized tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term ''Intelligen ...

as a score report. Based on his test findings, and reflecting the racism common to that era, Terman concluded that intellectual disability "represents the level of intelligence which is very, very common among Spanish-Indians and Mexican families of the Southwest and also among negroes. Their dullness seems to be racial."Guthrie, ''Even the Rat was White'' (1998), Chapter 3: "Psychometric Scientism" (pp. 55–87) Following the Army Alpha and Army Beta tests, which was developed by psychologist Robert Yerkes in 1917 and then used in World War 1 by industrial and organizational psychologists for large-scale employee testing and selection of military personnel. Mental testing also became popular in the U.S., where it was applied to schoolchildren. The federally created National Intelligence Test was administered to 7 million children in the 1920s. In 1926, the

College Entrance Examination Board The College Board is an American nonprofit organization that was formed in December 1899 as the College Entrance Examination Board (CEEB) to expand access to higher education. While the College Board is not an association of colleges, it runs a ...

created the

Scholastic Aptitude Test The SAT ( ) is a standardized test widely used for college admissions in the United States. Since its debut in 1926, its name and scoring have changed several times; originally called the Scholastic Aptitude Test, it was later called the Schol ...

to standardize college admissions. The results of intelligence tests were used to argue for segregated schools and economic functions, including the preferential training of Black Americans for manual labor. These practices were criticized by Black intellectuals such a

Horace Mann Bond Horace Mann Bond (November 8, 1904 – December 21, 1972) was an American historian, college administrator, social science researcher and the father of civil-rights leader Julian Bond. He earned a master's and doctorate from University of C ...

and Allison Davis. Eugenicists used mental testing to justify and organize compulsory sterilization of individuals classified as mentally retarded (now referred to as ''

intellectual disability Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...

''). In the United States, tens of thousands of men and women were sterilized. Setting a precedent that has never been overturned, the U.S. Supreme Court affirmed the constitutionality of this practice in the 1927 case '' Buck v. Bell''. Today mental testing is a routine phenomenon for people of all ages in Western societies. Modern testing aspires to criteria including standardization of procedure, consistency of results, output of an interpretable score, statistical norms describing population outcomes, and, ideally, effective prediction of behavior and life outcomes outside of testing situations. Psychological testing is regularly used in forensic contexts to aid legal judgments and decisions. Developments in psychometrics include work on test and scale

reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * High availability * Reliability (computer networking), a ...

and validity. Developments in

item-response theory In psychometrics, item response theory (IRT) (also known as latent trait theory, strong true score theory, or modern mental test theory) is a paradigm for the design, analysis, and scoring of tests, questionnaires, and similar instruments measurin ...

, structural equation modeling, and bifactor analysis have helped in strengthening test and scale construction.

Mental health care

The provision of psychological health services is generally called clinical psychology in the U.S. Sometimes, however, members of the school psychology and counseling psychology professions engage in practices that resemble that of clinical psychologists. Clinical psychologists typically include people who have graduated from doctoral programs in clinical psychology. In Canada, some of the members of the abovementioned groups usually fall within the larger category of professional psychology. In Canada and the U.S., practitioners get bachelor's degrees and doctorates; doctoral students in clinical psychology usually spend one year in a predoctoral internship and one year in postdoctoral internship. In Mexico and most other Latin American and European countries, psychologists do not get bachelor's and doctoral degrees; instead, they take a three-year professional course following high school. Clinical psychology is at present the largest specialization within psychology. It includes the study and application of psychology for the purpose of understanding, preventing, and relieving psychological distress, dysfunction, and/or mental illness. Clinical psychologists also try to promote subjective well-being and personal growth. Central to the practice of clinical psychology are psychological assessment and psychotherapy although clinical psychologists may also engage in research, teaching, consultation, forensic testimony, and program development and administration.Brain, Christine. (2002). ''Advanced psychology: applications, issues and perspectives.'' Cheltenham: Nelson Thornes. Credit for the first psychology clinic in the United States typically goes to

, who established his practice in Philadelphia in 1896. Another modern psychotherapist was

Morton Prince Morton Henry Prince (December 22, 1854 – August 31, 1929) was an American physician who specialized in neurology and abnormal psychology, and was a leading force in establishing psychology as a clinical and academic discipline. He was part o ...

, an early advocate for the establishment of psychology as a clinical and academic discipline.George Stricker & Thomas A. Widiger, "Volume Preface", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 8: ''Clinical Psychology''. In the first part of the twentieth century, most mental health care in the United States was performed by psychiatrists, who are medical doctors. Psychology entered the field with its refinements of mental testing, which promised to improve the diagnosis of mental problems. For their part, some psychiatrists became interested in using

and other forms of

psychodynamic psychotherapy Psychodynamic psychotherapy or psychoanalytic psychotherapy is a form of psychological therapy. Its primary focus is to reveal the unconscious content of a client's psyche in an effort to alleviate psychic tension, which is inner conflict wi ...

to understand and treat the mentally ill. Psychotherapy as conducted by psychiatrists blurred the distinction between psychiatry and psychology, and this trend continued with the rise of community mental health facilities. Some in the clinical psychology community adopted behavioral therapy, a thoroughly non-psychodynamic model that used behaviorist learning theory to change the actions of patients. A key aspect of behavior therapy is empirical evaluation of the treatment's effectiveness. In the 1970s, cognitive-behavior therapy emerged with the work of

and

Aaron Beck Aaron Temkin Beck (July 18, 1921 – November 1, 2021) was an American psychiatrist who was a professor in the department of psychiatry at the University of Pennsylvania.

. Although there are similarities between behavior therapy and cognitive-behavior therapy, cognitive-behavior therapy required the application of cognitive constructs. Since the 1970s, the popularity of cognitive-behavior therapy among clinical psychologists increased. A key practice in behavioral ''and'' cognitive-behavioral therapy is exposing patients to things they fear, based on the premise that their responses (fear, panic, anxiety) can be deconditioned. Mental health care today involves psychologists and social workers in increasing numbers. In 1977, National Institute of Mental Health director Bertram Brown described this shift as a source of "intense competition and role confusion."Nancy Tomes, "The Development of Clinical Psychology, Social Work, and Psychiatric Nursing: 1900–1980s", in Wallace & Gach (eds.), ''History of Psychiatry and Medical Psychology'' (2008). Graduate programs issuing doctorates in clinical psychology emerged in the 1950s and underwent rapid increase through the 1980s. The PhD degree is intended to train practitioners who could also conduct scientific research. The PsyD degree is more exclusively designed to train practitioners. Some clinical psychologists focus on the clinical management of patients with brain injury. This subspecialty is known as

clinical neuropsychology Clinical neuropsychology is a sub-field of psychology concerned with the applied science of brain-behaviour relationships. Clinical neuropsychologists use this knowledge in the assessment, diagnosis, treatment, and or rehabilitation of patients ...

. In many countries, clinical psychology is a regulated mental health profession. The emerging field of ''disaster psychology'' (see

crisis intervention Crisis intervention is a time-limited intervention with a specific psychotherapeutic approach to immediately stabilize those in crisis. Implementation A crisis can have physical or psychological effects. Usually significant and more widespre ...

) involves professionals who respond to large-scale traumatic events. The work performed by clinical psychologists tends to be influenced by various therapeutic approaches, all of which involve a formal relationship between professional and client (usually an individual, couple, family, or small group). Typically, these approaches encourage new ways of thinking, feeling, or behaving. Four major theoretical perspectives are psychodynamic, cognitive behavioral, existential–humanistic, and systems or family therapy. There has been a growing movement to integrate the various therapeutic approaches, especially with an increased understanding of issues regarding culture, gender, spirituality, and sexual orientation. With the advent of more robust research findings regarding psychotherapy, there is evidence that most of the major therapies have equal effectiveness, with the key common element being a strong

therapeutic alliance A therapeutic alliance, or working alliance, is a partnership between a patient and his or her therapist that allows them to achieve goals through agreed-upon tasks. The concept of therapeutic alliance dates back to Sigmund Freud. Over the cour ...

. Because of this, more training programs and psychologists are now adopting an eclectic therapeutic orientation. Diagnosis in clinical psychology usually follows the ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM). The study of mental illnesses is called

abnormal psychology Abnormal psychology is the branch of psychology that studies unusual patterns of behavior, emotion, and thought, which could possibly be understood as a mental disorder. Although many behaviors could be considered as abnormal, this branch of psyc ...

Education

Educational psychology Educational psychology is the branch of psychology concerned with the scientific study of human learning. The study of learning processes, from both cognitive and behavioral perspectives, allows researchers to understand individual differences in ...

is the study of how humans learn in educational settings, the effectiveness of educational interventions, the psychology of teaching, and the social psychology of

s as organizations. Educational psychologists can be found in preschools, schools of all levels including post secondary institutions, community organizations and learning centers, Government or private research firms, and independent or private consultant Madisonodell5/sandbox. The work of developmental psychologists such as Lev Vygotsky,

, and

Jerome Bruner Jerome Seymour Bruner (October 1, 1915 – June 5, 2016) was an American psychologist who made significant contributions to human cognitive psychology and cognitive learning theory in educational psychology. Bruner was a senior research fellow at ...

has been influential in creating teaching methods and educational practices. Educational psychology is often included in teacher education programs in places such as North America, Australia, and New Zealand. School psychology combines principles from educational psychology and clinical psychology to understand and treat students with learning disabilities; to foster the intellectual growth of

gifted Intellectual giftedness is an intellectual ability significantly higher than average. It is a characteristic of children, variously defined, that motivates differences in school programming. It is thought to persist as a trait into adult life, wi ...

students; to facilitate

prosocial behavior Prosocial behavior, or intent to benefit others, is a social behavior that "benefit other people or society as a whole", "such as helping, sharing, donating, co-operating, and volunteering". Obeying the rules and conforming to socially accepted beh ...

s in adolescents; and otherwise to promote safe, supportive, and effective learning environments. School psychologists are trained in educational and behavioral assessment, intervention, prevention, and consultation, and many have extensive training in research.

Work

Industrial and organizational (I/O) psychology involves research and practices that apply psychological theories and principles to organizations and individuals' work-lives. In the field's beginnings, industrialists brought the nascent field of psychology to bear on the study of scientific management techniques for improving workplace efficiency. The field was at first called ''economic psychology'' or ''business psychology''; later, ''industrial psychology'', ''employment psychology'', or ''psychotechnology''.Laura L. Koppes, "Industrial-Organizational Psychology", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 1: ''History of Psychology''. An influential early study examined workers at Western Electric's Hawthorne plant in Cicero, Illinois from 1924 to 1932. Western Electric experimented on factory workers to assess their responses to changes in illumination, breaks, food, and wages. The researchers came to focus on workers' responses to observation itself, and the term

Hawthorne effect The Hawthorne effect is a type of reactivity in which individuals modify an aspect of their behavior in response to their awareness of being observed. The effect was discovered in the context of research conducted at the Hawthorne Western Electric ...

is now used to describe the fact that people's behavior can change when they think they're being observed. Although the Hawthorne research can be found in psychology textbooks, the research and its findings were weak at best. The name industrial and organizational psychology emerged in the 1960s. In 1973, it became enshrined in the name of the Society for Industrial and Organizational Psychology, Division 14 of the American Psychological Association. One goal of the discipline is to optimize human potential in the workplace. Personnel psychology is a subfield of I/O psychology. Personnel psychologists apply the methods and principles of psychology in selecting and evaluating workers. Another subfield,

organizational psychology Industrial and organizational psychology (I-O psychology), an applied discipline within psychology, is the science of human behavior in the workplace. Depending on the country or region of the world, I-O psychology is also known as occupational ...

, examines the effects of work environments and management styles on worker motivation, job satisfaction, and productivity. Most I/O psychologists work outside of academia, for private and public organizations and as consultants. A psychology consultant working in business today might expect to provide executives with information and ideas about their industry, their target markets, and the organization of their company. Organizational behavior (OB) is an allied field involved in the study of human behavior within organizations. One way to differentiate I/O psychology from OB is to note that I/O psychologists train in university psychology departments and OB specialists, in business schools.

Military and intelligence

One role for psychologists in the military has been to evaluate and counsel soldiers and other personnel. In the U.S., this function began during World War I, when Robert Yerkes established the School of Military Psychology at Fort Oglethorpe in Georgia. The school provided psychological training for military staff. Today, U.S. Army psychologists perform psychological screening, clinical psychotherapy, suicide prevention, and treatment for post-traumatic stress, as well as provide prevention-related services, for example, smoking cessation. The United States Army's Mental Health Advisory Teams implement psychological interventions to help combat troops experiencing mental problems. Psychologists may also work on a diverse set of campaigns known broadly as psychological warfare. Psychological warfare chiefly involves the use of propaganda to influence enemy soldiers and civilians. This so-called black propaganda is designed to seem as if it originates from a source other than the Army. The CIA's

MKULTRA Project MKUltra (or MK-Ultra) was an illegal human experimentation program designed and undertaken by the U.S. Central Intelligence Agency (CIA), intended to develop procedures and identify drugs that could be used in interrogations to weak ...

program involved more individualized efforts at

mind control Brainwashing (also known as mind control, menticide, coercive persuasion, thought control, thought reform, and forced re-education) is the concept that the human mind can be altered or controlled by certain psychological techniques. Brainwashin ...

, involving techniques such as hypnosis, torture, and covert involuntary administration of

LSD Lysergic acid diethylamide (LSD), also known colloquially as acid, is a potent psychedelic drug. Effects typically include intensified thoughts, emotions, and sensory perception. At sufficiently high dosages LSD manifests primarily mental, vi ...

. The U.S. military used the name

Psychological Operations Psychological warfare (PSYWAR), or the basic aspects of modern psychological operations (PsyOp), have been known by many other names or terms, including Military Information Support Operations (MISO), Psy Ops, political warfare, "Hearts and M ...

(PSYOP) until 2010, when these activities were reclassified as Military Information Support Operations (MISO), part of Information Operations (IO). Psychologists have sometimes been involved in assisting the interrogation and torture of suspects, staining the records of the psychologists involved.

Health, well-being, and social change

Social change

An example of the contribution of psychologists to social change involves the research of

Kenneth Kenneth is an English given name and surname. The name is an Anglicised form of two entirely different Gaelic personal names: ''Cainnech'' and '' Cináed''. The modern Gaelic form of ''Cainnech'' is ''Coinneach''; the name was derived from a byn ...

and

Mamie Phipps Clark Mamie Phipps Clark (April 18, 1917 - August 11, 1983) was an African-American social psychologist who, along with her husband Kenneth Clark, focused on the development of self-consciousness in black preschool children. Clark was born and raised i ...

. These two African American psychologists studied segregation's adverse psychological impact on Black children. Their research findings played a role in the desegregation case ''

Brown v. Board of Education ''Brown v. Board of Education of Topeka'', 347 U.S. 483 (1954), was a landmark decision by the U.S. Supreme Court, which ruled that U.S. state laws establishing racial segregation in public schools are unconstitutional, even if the segrega ...

'' (1954). The impact of psychology on social change includes the discipline's broad influence on teaching and learning. Research has shown that compared to the "whole word" or "whole language" approach, the phonics approach to reading instruction is more efficacious.

Medical applications

Medical facilities increasingly employ psychologists to perform various roles. One aspect of health psychology is the

psychoeducation Psychoeducation (a portmanteau of psychological education) is an evidence-based therapeutic intervention for patients and their loved ones that provides information and support to better understand and cope with illness. Psychoeducation is most of ...

of patients: instructing them in how to follow a medical regimen. Health psychologists can also educate doctors and conduct research on patient compliance. Psychologists in the field of public health use a wide variety of interventions to influence human behavior. These range from public relations campaigns and outreach to governmental laws and policies. Psychologists study the composite influence of all these different tools in an effort to influence whole

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

s of people.

Worker health, safety and wellbeing

Psychologists work with organizations to apply findings from psychological research to improve the health and well-being of employees. Some work as external consultants hired by organizations to solve specific problems, whereas others are full-time employees of the organization. Applications include conducting surveys to identify issues and designing interventions to make work healthier. Some of the specific health areas include: *Accidents and injuries: A major contribution is the concept of safety climate, which is employee shared perceptions of the behaviors that are encouraged (e.g., wearing safety gear) and discouraged (not following safety rules) at work. Organizations with strong safety climates have fewer work accidents and injuries. * Cardiovascular disease: Cardiovascular disease has been related to lack of job control. *Mental health: Exposure to occupational stress is associated with mental health disorder. * Musculoskeletal disorder: These are injuries in bones, nerves and tendons due to overexertion and repetitive strain. They have been linked to job satisfaction and workplace stress. *Physical health symptoms: Occupational stress has been linked to physical symptoms such as digestive distress and headache. * Workplace violence: Violence prevention climate is related to being physically assaulted and psychologically mistreated at work. Interventions that improve climates are a way to address accidents and violence. Interventions that reduce stress at work or provide employees with tools to better manage it can help in areas where stress is an important component. Industrial psychology became interested in worker fatigue during World War I, when government ministers in Britain were concerned about the impact of fatigue on workers in munitions factories but not other types of factories.Kreis, S. (1995). Early experiments in British scientific management: the Health of Munitions Workers' Committee, 1915-1920. ''Journal of Management History (archive), 1'', 65-78. doi.org/10.1108/13552529510088330 In the U. K. some interest in worker

well-being Well-being, or wellbeing, also known as wellness, prudential value or quality of life, refers to what is intrinsically valuable relative ''to'' someone. So the well-being of a person is what is ultimately good ''for'' this person, what is in th ...

emerged with the efforts of Charles Samuel Myers and his National Institute of Industrial Psychology (NIIP) during the inter-War years. In the U. S. during the mid-twentieth century industrial psychologist

Arthur Kornhauser Arthur William Kornhauser (November 23, 1896 – December 11, 1990) was an American industrial psychologist. He was an early researcher on topics such as labor unions and worker attitudes, and advocated a form of industrial psychology that appro ...

pioneered the study of occupational mental health, linking industrial working conditions to mental health as well as the spillover of an unsatisfying job into a worker's personal life.Zickar, M. J. (2003). Remembering Arthur Kornhauser: Industrial psychology's advocate for worker well-being. ''Journal of Applied Psychology, 88'', 363–369. Zickar accumulated evidence to show that "no other industrial psychologist of his era was as devoted to advocating management and labor practices that would improve the lives of working people."

Occupational health psychology

As interest in the worker health expanded toward the end of the twentieth century, the field of occupational health psychology (OHP) emerged. OHP is a branch of psychology that is interdisciplinary.Spector, P. E. (2021). From occupational fatigue to occupational health. In L. M. Lapierre & C. Cooper (Eds.). ''Cambridge companion to organizational stress and well-being''. New York: Cambridge University Press.Centers for Disease Control and Prevention. ''Occupational Health Psychology (OHP)''

OHP is concerned with the health and safety of workers. OHP addresses topic areas such as the impact of occupational stressors on physical and mental health, mistreatment of workers (e.g., bullying and violence), work-family balance, the impact of involuntary unemployment on physical and mental health, the influence of psychosocial factors on safety and accidents, and interventions designed to improve/protect worker health. OHP grew out of

health psychology Health psychology is the study of psychological and behavioral processes in health, illness, and healthcare. The discipline is concerned with understanding how psychological, behavioral, and cultural factors contribute to physical health and illn ...

industrial and organizational psychology Industrial and organizational psychology (I-O psychology), an applied discipline within psychology, is the science of human behavior in the workplace. Depending on the country or region of the world, I-O psychology is also known as occupational ...

, and occupational medicine.Everly, G.S., Jr. (1986). An introduction to occupational health psychology. In P.A. Keller & L.G. Ritt (Eds.), ''Innovations in clinical practice: A source book'' (Vol. 5, pp. 331–338). Sarasota, FL: Professional Resource Exchange. OHP has also been informed by disciplines outside psychology, including

industrial engineering Industrial engineering is an engineering profession that is concerned with the optimization of complex processes, systems, or organizations by developing, improving and implementing integrated systems of people, money, knowledge, information a ...

sociology Sociology is a social science that focuses on society, human social behavior, patterns of social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of empirical investigation an ...

, and

economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...

Research methods

Quantitative psychological research lends itself to the statistical testing of hypotheses. Although the field makes abundant use of randomized and controlled experiments in laboratory settings, such research can only assess a limited range of short-term phenomena. Some psychologists rely on less rigorously controlled, but more ecologically valid,

field experiments Field experiments are experiments carried out outside of laboratory settings. They randomly assign subjects (or other sampling units) to either treatment or control groups in order to test claims of causal relationships. Random assignment help ...

as well. Other research psychologists rely on statistical methods to glean knowledge from population data. The statistical methods research psychologists employ include the Pearson product–moment correlation coefficient, the

analysis of variance Analysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among means. ANOVA was developed by the statistician ...

multiple linear regression In statistics, linear regression is a linear approach for modelling the relationship between a scalar response and one or more explanatory variables (also known as dependent and independent variables). The case of one explanatory variable is cal ...

logistic regression In statistics, the logistic model (or logit model) is a statistical model that models the probability of an event taking place by having the log-odds for the event be a linear combination of one or more independent variables. In regression a ...

, structural equation modeling, and

hierarchical linear modeling Multilevel models (also known as hierarchical linear models, linear mixed-effect model, mixed models, nested data models, random coefficient, random-effects models, random parameter models, or split-plot designs) are statistical models of parame ...

. The measurement and

operationalization In research design, especially in psychology, social sciences, life sciences and physics, operationalization or operationalisation is a process of defining the measurement of a phenomenon which is not directly measurable, though its existence is in ...

of important constructs is an essential part of these research designs. Although this type of psychological research is much less abundant than quantitative research, some psychologists conduct

qualitative research Qualitative research is a type of research that aims to gather and analyse non-numerical (descriptive) data in order to gain an understanding of individuals' social reality, including understanding their attitudes, beliefs, and motivation. This ...

. This type of research can involve interviews, questionnaires, and first-hand observation. While hypothesis testing is rare, virtually impossible, in qualitative research, qualitative studies can be helpful in theory and hypothesis generation, interpreting seemingly contradictory quantitative findings, and understanding why some interventions fail and others succeed.

Controlled experiments

Flowchart of Phases of Parallel Randomized Trial - Modified from CONSORT 2010

A true experiment with

random In common usage, randomness is the apparent or actual lack of pattern or predictability in events. A random sequence of events, symbols or steps often has no order and does not follow an intelligible pattern or combination. Individual ra ...

assignment of research participants (sometimes called subjects) to rival conditions allows researchers to make strong inferences about causal relationships. When there are large numbers of research participants, the random assignment (also called random allocation) of those participants to rival conditions ensures that the individuals in those conditions will, on average, be similar on most characteristics, including characteristics that went unmeasured. In an experiment, the researcher alters one or more variables of influence, called independent variables, and measures resulting changes in the factors of interest, called dependent variables. Prototypical experimental research is conducted in a laboratory with a carefully controlled environment. A

quasi-experiment A quasi-experiment is an empirical interventional study used to estimate the causal impact of an intervention on target population without random assignment. Quasi-experimental research shares similarities with the traditional experimental design ...

refers to a situation in which there are rival conditions under study but random assignment to the different conditions is not possible. Investigators must work with preexisting groups of people. Researchers can use common sense to consider how much the nonrandom assignment threatens the study's validity. For example, in research on the best way to affect reading achievement in the first three grades of school, school administrators may not permit educational psychologists to randomly assign children to phonics and whole language classrooms, in which case the psychologists must work with preexisting classroom assignments. Psychologists will compare the achievement of children attending phonics and whole language classes and, perhaps, statistically adjust for any initial differences in reading level. Experimental researchers typically use a statistical hypothesis testing model which involves making predictions before conducting the experiment, then assessing how well the data collected are consistent with the predictions. These predictions are likely to originate from one or more abstract scientific hypotheses about how the phenomenon under study actually works.

Other types of studies

Surveys are used in psychology for the purpose of measuring attitudes and traits, monitoring changes in mood, and checking the validity of experimental manipulations (checking research participants' perception of the condition they were assigned to). Psychologists have commonly used paper-and-pencil surveys. However, surveys are also conducted over the phone or through e-mail. Web-based surveys are increasingly used to conveniently reach many subjects.

Observational studies In fields such as epidemiology, social sciences, psychology and statistics, an observational study draws inferences from a sample to a population where the independent variable is not under the control of the researcher because of ethical concern ...

are commonly conducted in psychology. In cross-sectional observational studies, psychologists collect data at a single point in time. The goal of many cross-sectional studies is the assess the extent factors are correlated with each other. By contrast, in

longitudinal studies A longitudinal study (or longitudinal survey, or panel study) is a research design that involves repeated observations of the same variables (e.g., people) over short or long periods of time (i.e., uses longitudinal data). It is often a type of obs ...

psychologists collect data on the same sample at two or more points in time. Sometimes the purpose of longitudinal research is to study trends across time such as the stability of traits or age-related changes in behavior. Because some studies involve endpoints that psychologists cannot ethically study from an experimental standpoint, such as identifying the causes of depression, they conduct longitudinal studies a large group of depression-free people, periodically assessing what is happening in the individuals' lives. In this way psychologists have an opportunity to test causal hypotheses regarding conditions that commonly arise in people's lives that put them at risk for depression. Problems that affect longitudinal studies include selective attrition, the type of problem in which bias is introduced when a certain type of research participant disproportionately leaves a study.

Exploratory data analysis In statistics, exploratory data analysis (EDA) is an approach of analyzing data sets to summarize their main characteristics, often using statistical graphics and other data visualization methods. A statistical model can be used or not, but pri ...

refers to a variety of practices that researchers use to reduce a great many variables to a small number overarching factors. In Peirce's three modes of inference, exploratory data analysis corresponds to abduction.

Meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

is the technique research psychologists use to integrate results from many studies of the same variables and arriving at a grand average of the findings.

Direct brain observation/manipulation

A classic and popular tool used to relate mental and neural activity is the

electroencephalogram Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

(EEG), a technique using amplified electrodes on a person's scalp to measure voltage changes in different parts of the brain.

Hans Berger Hans Berger (21 May 1873 – 1 June 1941) was a German psychiatrist. He is best known as the inventor of electroencephalography (EEG) in 1924, which is a method used for recording the electrical activity of the brain, commonly described in terms ...

, the first researcher to use EEG on an unopened skull, quickly found that brains exhibit signature "brain waves": electric oscillations which correspond to different states of consciousness. Researchers subsequently refined statistical methods for synthesizing the electrode data, and identified unique brain wave patterns such as the

delta wave Delta waves are high amplitude neural oscillations with a frequency between 0.5 and 4 hertz. Delta waves, like other brain waves, can be recorded with electroencephalography (EEG) and are usually associated with the deep stage 3 of NREM sleep, ...

observed during non-REM sleep. Newer

functional neuroimaging Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions. It is primarily used a ...

techniques include functional magnetic resonance imaging and positron emission tomography, both of which track the flow of blood through the brain. These technologies provide more localized information about activity in the brain and create representations of the brain with widespread appeal. They also provide insight which avoids the classic problems of subjective self-reporting. It remains challenging to draw hard conclusions about where in the brain specific thoughts originate—or even how usefully such localization corresponds with reality. However, neuroimaging has delivered unmistakable results showing the existence of correlations between mind and brain. Some of these draw on a systemic neural network model rather than a localized function model. Interventions such as

transcranial magnetic stimulation Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse gener ...

and drugs also provide information about brain–mind interactions.

Psychopharmacology Psychopharmacology (from Greek grc, ψῡχή, psȳkhē, breath, life, soul, label=none; grc, φάρμακον, pharmakon, drug, label=none; and grc, -λογία, -logia, label=none) is the scientific study of the effects drugs have on mo ...

is the study of drug-induced mental effects. Multi-Layer Neural Network-Vector

Computer simulation

Computational modeling is a tool used in mathematical psychology and cognitive psychology to simulate behavior. This method has several advantages. Since modern computers process information quickly, simulations can be run in a short time, allowing for high statistical power. Modeling also allows psychologists to visualize hypotheses about the functional organization of mental events that couldn't be directly observed in a human. Computational neuroscience uses mathematical models to simulate the brain. Another method is symbolic modeling, which represents many mental objects using variables and rules. Other types of modeling include dynamic systems and stochastic modeling.

Animal studies

Animal experiments aid in investigating many aspects of human psychology, including perception, emotion, learning, memory, and thought, to name a few. In the 1890s, Russian physiologist Ivan Pavlov famously used dogs to demonstrate classical conditioning. Non-human primates, cats, dogs, pigeons, and rats and other rodents are often used in psychological experiments. Ideally, controlled experiments introduce only one independent variable at a time, in order to ascertain its unique effects upon dependent variables. These conditions are approximated best in laboratory settings. In contrast, human environments and genetic backgrounds vary so widely, and depend upon so many factors, that it is difficult to control important variables for human subjects. There are pitfalls, however, in generalizing findings from animal studies to humans through animal models. Comparative psychology refers to the scientific study of the behavior and mental processes of non-human animals, especially as these relate to the phylogenetic history, adaptive significance, and development of behavior. Research in this area explores the behavior of many species, from insects to primates. It is closely related to other disciplines that study animal behavior such as

ethology Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objecti ...

. Research in comparative psychology sometimes appears to shed light on human behavior, but some attempts to connect the two have been quite controversial, for example the

Sociobiology Sociobiology is a field of biology that aims to examine and explain social behavior in terms of evolution. It draws from disciplines including psychology, ethology, anthropology, evolution, zoology, archaeology, and population genetics. Within ...

of E.O. Wilson. Animal models are often used to study neural processes related to human behavior, e.g. in cognitive neuroscience.

Qualitative research

Qualitative research is often designed to answer questions about the thoughts, feelings, and behaviors of individuals. Qualitative research involving first-hand observation can help describe events as they occur, with the goal of capturing the richness of everyday behavior and with the hope of discovering and understanding phenomena that might have been missed if only more cursory examinations are made. Qualitative psychological research methods include interviews, first-hand observation, and participant observation. Creswell (2003) identified five main possibilities for qualitative research, including narrative, phenomenology, ethnography,

case study A case study is an in-depth, detailed examination of a particular case (or cases) within a real-world context. For example, case studies in medicine may focus on an individual patient or ailment; case studies in business might cover a particular fi ...

, and

grounded theory Grounded theory is a systematic methodology that has been largely applied to qualitative research conducted by social scientists. The methodology involves the construction of hypotheses and theories through the collecting and analysis of data. G ...

. Qualitative researchers sometimes aim to enrich our understanding of symbols, subjective experiences, or social structures. Sometimes

hermeneutic Hermeneutics () is the theory and methodology of interpretation, especially the interpretation of biblical texts, wisdom literature, and philosophical texts. Hermeneutics is more than interpretative principles or methods used when immediate c ...

and critical aims can give rise to quantitative research, as in Erich Fromm's application of psychological and sociological theories, in his book ''

Escape from Freedom ''Escape from Freedom'' is a book by the Frankfurt-born psychoanalyst Erich Fromm, first published in the United States by Farrar & Rinehart in 1941 with the title ''Escape from Freedom'' and a year later as ''The Fear of Freedom'' in UK by Ro ...

'', to understanding why many ordinary Germans supported Hitler. Phineas gage - 1868 skull diagram

Just as

Jane Goodall Dame Jane Morris Goodall (; born Valerie Jane Morris-Goodall on 3 April 1934), formerly Baroness Jane van Lawick-Goodall, is an English primatologist and anthropologist. Seen as the world's foremost expert on chimpanzees, Goodall is best kn ...

studied chimpanzee social and family life by careful observation of chimpanzee behavior in the field, psychologists conduct

naturalistic observation Naturalistic observation, sometimes referred to as fieldwork, is a research methodology in numerous fields of science including ethology, anthropology, linguistics, the social sciences, and psychology, in which data are collected as they occur i ...

of ongoing human social, professional, and family life. Sometimes the participants are aware they are being observed, and other times the participants do not know they are being observed. Strict ethical guidelines must be followed when covert observation is being carried out.

Program evaluation

Program evaluation Program evaluation is a systematic method for collecting, analyzing, and using information to answer questions about projects, policies and programs, particularly about their effectiveness and efficiency. In both the public and private sectors, s ...

involves the systematic collection, analysis, and application of information to answer questions about projects, policies and programs, particularly about their effectiveness. In both the public and private sectors, stakeholders often want to know the extent which the programs they are funding, implementing, voting for, receiving, or objecting to are producing the intended effects. While program evaluation first focuses on effectiveness, important considerations often include how much the program costs per participant, how the program could be improved, whether the program is worthwhile, whether there are better alternatives, if there are unintended outcomes, and whether the program goals are appropriate and useful.

Contemporary issues in methodology and practice

Metascience

Metascience involves the application of scientific methodology to study science itself. The field of

metascience Metascience (also known as meta-research) is the use of scientific methodology to study science itself. Metascience seeks to increase the quality of scientific research while reducing inefficiency. It is also known as "''research on research''" ...

has revealed problems in psychological research. Some psychological research has suffered from

bias Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, ...

, problematic

reproducibility Reproducibility, also known as replicability and repeatability, is a major principle underpinning the scientific method. For the findings of a study to be reproducible means that results obtained by an experiment or an observational study or in a ...

, and

misuse of statistics Statistics, when used in a misleading fashion, can trick the casual observer into believing something other than what the data shows. That is, a misuse of statistics occurs when a statistical argument asserts a falsehood. In some cases, the misu ...

. These findings have led to calls for reform from within and from outside the scientific community.

Confirmation bias

In 1959, statistician Theodore Sterling examined the results of psychological studies and discovered that 97% of them supported their initial hypotheses, implying possible

publication bias In published academic research, publication bias occurs when the outcome of an experiment or research study biases the decision to publish or otherwise distribute it. Publishing only results that show a significant finding disturbs the balance o ...

. Similarly, Fanelli (2010) found that 91.5% of psychiatry/psychology studies confirmed the effects they were looking for, and concluded that the odds of this happening (a positive result) was around five times higher than in fields such as

space science Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...

geoscience Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical, chemical, and biological complex constitutions and synergistic linkages of Earth's four spheres ...

s. Fanelli argued that this is because researchers in "softer" sciences have fewer constraints to their conscious and unconscious biases.

Replication

replication crisis The replication crisis (also called the replicability crisis and the reproducibility crisis) is an ongoing methodological crisis in which the results of many scientific studies are difficult or impossible to reproduce. Because the reproducibili ...

in psychology has emerged. Many notable findings in the field have not been replicated. Some researchers were even accused of publishing fraudulent results. Systematic efforts, including efforts by the Reproducibility Project of the

Center for Open Science The Center for Open Science is a non-profit technology organization based in Charlottesville, Virginia with a mission to "increase the openness, integrity, and reproducibility of scientific research." Brian Nosek and Jeffrey Spies founded the or ...

, to assess the extent of the problem found that as many as two-thirds of highly publicized findings in psychology failed to be replicated. Reproducibility has generally been stronger in cognitive psychology (in studies and journals) than social psychology and subfields of

differential psychology Differential psychology studies the ways in which individuals differ in their behavior and the processes that underlie it. This is a discipline that develops classifications (taxonomies) of psychological individual differences. This is distingui ...

. Other subfields of psychology have also been implicated in the replication crisis, including clinical psychology, developmental psychology, and a field closely related to psychology,

educational research Educational research refers to the systematic collection and analysis of data related to the field of education. Research may involve a variety of methods and various aspects of education including student learning, teaching methods, teacher tra ...

. Focus on the replication crisis has led to other renewed efforts in the discipline to re-test important findings. In response to concerns about publication bias and data dredging (conducting a large number of statistical tests on a great many variables but restricting reporting to the results that were statistically significant), 295 psychology and medical journals have adopted result-blind peer review where studies are accepted not on the basis of their findings and after the studies are completed, but before the studies are conducted and upon the basis of the methodological rigor of their experimental designs and the theoretical justifications for their proposed statistical analysis before data collection or analysis is conducted. In addition, large-scale collaborations among researchers working in multiple labs in different countries have taken place. The collaborators regularly make their data openly available for different researchers to assess. Allen and Mehler estimated that 61 percent of result-blind studies have yielded

null result In science, a null result is a result without the expected content: that is, the proposed result is absent. It is an experimental outcome which does not show an otherwise expected effect. This does not imply a result of zero or nothing, simply a res ...

s, in contrast to an estimated 5 to 20 percent in traditional research.

Misuse of statistics

Some critics view

statistical hypothesis testing A statistical hypothesis test is a method of statistical inference used to decide whether the data at hand sufficiently support a particular hypothesis. Hypothesis testing allows us to make probabilistic statements about population parameters. ...

as misplaced. Psychologist and statistician Jacob Cohen wrote in 1994 that psychologists routinely confuse statistical significance with practical importance, enthusiastically reporting great certainty in unimportant facts. Some psychologists have responded with an increased use of

effect size In statistics, an effect size is a value measuring the strength of the relationship between two variables in a population, or a sample-based estimate of that quantity. It can refer to the value of a statistic calculated from a sample of data, the ...

statistics, rather than sole reliance on ''p''-values.

WEIRD bias

In 2008, Arnett pointed out that most articles in American Psychological Association journals were about U.S. populations when U.S. citizens are only 5% of the world's population. He complained that psychologists had no basis for assuming psychological processes to be universal and generalizing research findings to the rest of the global population. In 2010, Henrich, Heine, and Norenzayan reported a bias in conducting psychology studies with participants from "''WEIRD''" ("Western, Educated, Industrialized, Rich, and Democratic") societies. Henrich et al. found that "96% of psychological samples come from countries with only 12% of the world’s population" (p. 63). The article gave examples of results that differ significantly between people from WEIRD and tribal cultures, including the

Müller-Lyer illusion The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they tend to place it more towards the "tail" end. The illusion was devised by Franz Carl ...

. Arnett (2008), Altmaier and Hall (2008) and Morgan-Consoli et al. (2018) view the Western bias in research and theory as a serious problem considering psychologists are increasingly applying psychological principles developed in WEIRD regions in their research, clinical work, and consultation with populations around the world. In 2018, Rad, Martingano, and Ginges showed that nearly a decade after Henrich et al.'s paper, over 80% of the samples used in studies published in the journal

Psychological Science ''Psychological Science'', the flagship journal of the Association for Psychological Science (APS), is a monthly, peer-reviewed, scientific journal published by SAGE Publications. Publication scope ''Psychological Science'' publishes research r ...

employed WEIRD samples. Moreover, their analysis showed that several studies did not fully disclose the origin of their samples; the authors offered a set of recommendations to editors and reviewers to reduce WEIRD bias.

Unscientific mental health training

Some observers perceive a gap between scientific theory and its application—in particular, the application of unsupported or unsound clinical practices. Critics say there has been an increase in the number of mental health training programs that do not instill scientific competence. Practices such as "

facilitated communication Facilitated communication (FC), or supported typing, is a scientifically discredited technique that attempts to aid communication by people with autism or other communication disabilities who are non-verbal. The facilitator guides the disabled ...

for infantile autism"; memory-recovery techniques including body work; and other therapies, such as rebirthing and

reparenting Reparenting is a form of psychotherapy in which the therapist actively assumes the role of a new or surrogate parental figure for the client, in order to treat psychological disturbances caused by defective, even abusive, parenting. The underlyin ...

, may be dubious or even dangerous, despite their popularity. These practices, however, are outside the mainstream practices taught in clinical psychology doctoral programs.

Ethics

Ethical standards in the discipline have changed over time. Some famous past studies are today considered unethical and in violation of established codes (the Canadian Code of Conduct for Research Involving Humans, and the

Belmont Report The ''Belmont Report'' is a report created by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. Its full title is the ''Belmont Report: Ethical Principles and Guidelines for the Protection of Human ...

). The American Psychological Association has advanced a set of ethical principles and a code of conduct for the profession. The most important contemporary standards include informed and voluntary consent. After World War II, the

Nuremberg Code The Nuremberg Code (german: Nürnberger Kodex) is a set of ethical research principles for human experimentation created by the court in '' U.S. v Brandt'', one of the Subsequent Nuremberg trials that were held after the Second World War. Tho ...

was established because of Nazi abuses of experimental subjects. Later, most countries (and scientific journals) adopted the

Declaration of Helsinki The Declaration of Helsinki (DoH, fi, Helsingin julistus, sv, Helsingforsdeklarationen) is a set of ethical principles regarding human experimentation developed originally in 1964 for the medical community by the World Medical Association (WMA) ...

. In the U.S., the

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...

established the

Institutional Review Board An institutional review board (IRB), also known as an independent ethics committee (IEC), ethical review board (ERB), or research ethics board (REB), is a committee that applies research ethics by reviewing the methods proposed for research to ens ...

in 1966, and in 1974 adopted the

National Research Act The National Research Act was enacted by the 93rd United States Congress and signed into law by President Richard Nixon on July 12, 1974, after a series of congressional hearings on human-subjects research, directed by Senator Edward Kennedy. The ...

(HR 7724). All of these measures encouraged researchers to obtain informed consent from human participants in experimental studies. A number of influential but ethically dubious studies led to the establishment of this rule; such studies included the MIT-Harvard Fernald School radioisotope studies, the Thalidomide tragedy, the Willowbrook hepatitis study, and Stanley Milgram's studies of obedience to authority.

Humans

Universities have ethics committees dedicated to protecting the rights (e.g., voluntary nature of participation in the research, privacy) and well-being (e.g., minimizing distress) of research participants. University ethics committees evaluate proposed research to ensure that researchers protect the rights and well-being of participants; an investigator's research project cannot be conducted unless approved by such an ethics committee. The ethics code of the American Psychological Association originated in 1951 as "Ethical Standards of Psychologists". This code has guided the formation of licensing laws in most American states. It has changed multiple times over the decades since its adoption. In 1989, the APA revised its policies on advertising and referral fees to negotiate the end of an investigation by the Federal Trade Commission. The 1992 incarnation was the first to distinguish between "aspirational" ethical standards and "enforceable" ones. Members of the public have a five-year window to file ethics complaints about APA members with the APA ethics committee; members of the APA have a three-year window.Stanley E. Jones, "Ethical Issues in Clinical Psychology", in Weiner (ed.), ''Handbook of Psychology'' (2003), Volume 8: ''Clinical Psychology''. Some of the ethical issues considered most important are the requirement to practice only within the area of competence, to maintain confidentiality with the patients, and to avoid sexual relations with them. Another important principle is

informed consent Informed consent is a principle in medical ethics and medical law, that a patient must have sufficient information and understanding before making decisions about their medical care. Pertinent information may include risks and benefits of treatme ...

, the idea that a patient or research subject must understand and freely choose a procedure they are undergoing. Some of the most common complaints against clinical psychologists include sexual misconduct.

Other animals

Research on other animals is also governed by university ethics committees. Research on nonhuman animals cannot proceed without permission of the ethics committee of the researcher's home institution. Current ethical guidelines state that using non-human animals for scientific purposes is only acceptable when the harm (physical or psychological) done to animals is outweighed by the benefits of the research. Keeping this in mind, psychologists can use certain research techniques on animals that could not be used on humans. * Comparative psychologist

Harry Harlow Harry Frederick Harlow (October 31, 1905 – December 6, 1981) was an American psychologist best known for his maternal-separation, dependency needs, and social isolation experiments on rhesus monkeys, which manifested the importance of caregi ...

drew moral condemnation for isolation experiments on rhesus macaque monkeys at the

University of Wisconsin–Madison A university () is an educational institution, institution of higher education, higher (or Tertiary education, tertiary) education and research which awards academic degrees in several Discipline (academia), academic disciplines. Universities ty ...

in the 1970s. The aim of the research was to produce an animal model of clinical depression. Harlow also devised what he called a "rape rack", to which the female isolates were tied in normal monkey mating posture. In 1974, American literary critic

Wayne C. Booth Wayne Clayson Booth (February 22, 1921, in American Fork, Utah – October 10, 2005, in Chicago, Illinois) was an American literary critic. He was the George M. Pullman Distinguished Service Professor Emeritus in English Language & Literature an ...

wrote that, "Harry Harlow and his colleagues go on torturing their nonhuman primates decade after decade, invariably proving what we all knew in advance—that social creatures can be destroyed by destroying their social ties." He writes that Harlow made no mention of the criticism of the morality of his work.Booth, Wayne C. ''Modern Dogma and the Rhetoric of Assent'', Volume 5, of University of Notre Dame, Ward-Phillips lectures in English language and literature, University of Chicago Press, 1974, p. 114. Booth is explicitly discussing this experiment. His next sentence is, "His most recent outrage consists of placing monkeys in 'solitary' for twenty days—what he calls a 'vertical chamber apparatus .... designed on an intuitive basis' to produce 'a state of helplessness and hopelessness, sunken in a well of despair.

References

Sources

* Baker, David B. (ed.). ''The Oxford Handbook of the History of Psychology''. Oxford University Press (''Oxford Library of Psychology''), 2012. * Brock, Adrian C. (ed.). ''Internationalizing the History of Psychology''. New York University Press, 2006. * Cina, Carol. "Social Science for Whom? A Structural History of Social Psychology." Doctoral dissertation, accepted by the State University of New York at Stony Brook, 1981. * Cocks, Geoffrey. ''Psychotherapy in the Third Reich: The Göring Institute'', second edition. New Brunswick, NJ: Transaction Publishers, 1997. * Forgas, Joseph P., Kipling D. Williams, & Simon M. Laham. ''Social Motivation: Conscious and Unconscious Processes''. Cambridge University Press, 2005. * Guthrie, Robert. ''Even the Rat was White: A Historical View of Psychology''. Second edition. Boston, Allyn and Bacon (Viacon), 1998. * Herman, Ellen. "Psychology as Politics: How Psychological Experts Transformed Public Life in the United States 1940–1970." Doctoral dissertation accepted by Brandeis University, 1993. * Hock, Roger R. ''

Forty Studies That Changed Psychology ''Forty Studies That Changed Psychology: Explorations Into the History of Psychological Research'' is an academic textbook written by Roger R. Hock that is currently in its eighth edition. The book provides summaries, critiques, and updates on imp ...

: Explorations Into the History of Psychological Research''. Fourth edition. Upper Saddle River, NJ: Prentice Hall, 2002. * Morgan, Robert D., Tara L. Kuther, & Corey J. Habben. ''Life After Graduate School in Psychology: Insider's Advice from New Psychologists''. New York: Psychology Press (Taylor & Francis Group), 2005. * Severin, Frank T. (ed.). ''Humanistic Viewpoints in Psychology'': A Book of Readings. New York: McGraw Hill, 1965. ISBN * Shah, James Y., and Wendi L. Gardner. ''Handbook of Motivation Science''. New York: The Guilford Press, 2008. * Wallace, Edwin R., IV, & John Gach (eds.), ''History of Psychiatry and Medical Psychology''; New York: Springer, 2008; * Weiner, Bernard. ''Human Motivation''. Hoboken, NJ: Taylor and Francis, 2013. * Weiner, Irving B. ''Handbook of Psychology''. Hoboken, NJ: John Wiley & Sons, 2003. ** Volume 1: ''History of Psychology''. Donald K. Freedheim, ed. ** Volume 2: ''Research Methods in Psychology''. John A. Schinka & Wayne F. Velicer, eds. ** Volume 3: ''Biological Psychology''. Michela Gallagher & Randy J. Nelson, eds. ** Volume 4: ''Experimental Psychology''. Alice F. Healy & Robert W. Proctor, eds. ** Volume 8: ''Clinical Psychology''. George Stricker, Thomas A. Widiger, eds.

External links

*
American Psychological Association

Association for Psychological Science
{{Authority control Behavioural sciences Cognitive behavioral therapy

Etymology and definitions

History

Beginning of experimental psychology

Consolidation and funding

Disciplinary organization

Institutions

Boundaries

Major schools of thought

Biological

Behaviorist

Cognitive

Social

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Existential-humanistic

Themes

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Unconscious mind

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Development psychology

Genes and environment

Applications

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Health, well-being, and social change

Social change

Medical applications

Worker health, safety and wellbeing

Occupational health psychology

Research methods

Controlled experiments

Other types of studies

Direct brain observation/manipulation

Computer simulation

Animal studies

Qualitative research

Program evaluation

Contemporary issues in methodology and practice

Metascience

Confirmation bias

Replication

Misuse of statistics

WEIRD bias

Unscientific mental health training

Ethics

Humans

Other animals

References

Sources

Further reading

External links