![XYZ model](https://upload.wikimedia.org/wikipedia/commons/3/30/XYZ_model.jpg)
Body relative directions (also known as egocentric coordinates)
are
geometrical orientations relative to a body such as a
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
person's.
The most common ones are: left and right; forward(s) and backward(s); up and down.
They form three pairs of
orthogonal
In mathematics, orthogonality is the generalization of the geometric notion of ''perpendicularity''.
By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in ...
axes.
Traditions and conventions
Since definitions of left and right based on the geometry of the natural environment are unwieldy, in practice, the meaning of relative direction words is conveyed through
tradition
A tradition is a belief or behavior (folk custom) passed down within a group or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or ...
,
acculturation
Acculturation is a process of social, psychological, and cultural change that stems from the balancing of two cultures while adapting to the prevailing culture of the society. Acculturation is a process in which an individual adopts, acquires and ...
,
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. Va ...
, and direct reference. One common definition of up and down uses
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
and the
planet Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface ...
as a frame of reference. Since there is a very noticeable force of gravity acting between the Earth and any other nearby object, down is defined as that direction which an object moves in reference to the Earth when the object is allowed to
fall freely. Up is then defined as the opposite direction of down. Another common definition uses a human body, standing upright, as a frame of reference. In that case, up is defined as the direction from feet to head, perpendicular to the surface of the Earth. In most cases, up is a directionally oriented position generally opposite to that of the pull of gravity.
![Orestes (1848)](https://upload.wikimedia.org/wikipedia/commons/c/cb/Orestes_%281848%29.jpg)
In situations where a common frame of reference is needed, it is most common to use an egocentric view. A simple example is road signage. Another example is
stage blocking, where "stage left" "stage right" are, by convention, defined from the point of view of actors facing the audience. "Upstage" and "downstage" do not follow gravity but by convention mean away from and towards the audience. An example of a non-egocentric view is
page layout
In graphic design, page layout is the arrangement of visual elements on a page. It generally involves organizational principles of composition to achieve specific communication objectives.
The high-level page layout involves deciding on the ov ...
, where the relative terms "upper half" "left margin," etc. are defined in terms of the observer but employed in reverse for a
type compositor, returning to an egocentric view. In medicine and science, where precise definitions are crucial, relative directions (left and right) are the sides of the organism, not those of the observer. The same is true in heraldry, where left and right in a
coat of arms
A coat of arms is a heraldry, heraldic communication design, visual design on an escutcheon (heraldry), escutcheon (i.e., shield), surcoat, or tabard (the latter two being outer garments). The coat of arms on an escutcheon forms the central ele ...
is treated as if the shield were being held by the armiger. To avoid confusion, Latin terminology is employed: ''dexter'' and ''sinister'' for right and left.
Proper right and proper left
Proper right and proper left are conceptual terms used to unambiguously convey relative direction when describing an image or other object. The "proper right" hand of a figure is the hand that would be regarded by that figure as its right hand. ...
are terms mainly used to describe artistic images, and overcome the potential confusion that a figure's "own" right or "proper right" hand is on the left hand as the viewer sees it from the front.
Forward and backward may be defined by referring to an object's or person's
motion
In physics, motion is the phenomenon in which an object changes its position with respect to time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed and frame of reference to an observer and mea ...
. Forward is defined as the direction in which the object is moving. Backward is then defined as the opposite direction to forward. Alternatively, 'forward' may be the direction pointed by the observer's
nose
A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes th ...
, defining 'backward' as the direction from the nose to the
sagittal border in the observer's
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
. With respect to a ship 'forward' would indicate the relative position of any object lying in the direction the ship is pointing. For symmetrical objects, it is also necessary to define forward and backward in terms of expected direction. Many mass transit trains are built symmetrically with paired control booths, and definitions of forward, backward, left, and right are temporary.
Given significant distance from the
magnetic poles, one can figure which hand is which using a
magnetic compass
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with ...
and the
sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. Facing the sun, before noon, the north pointer of the compass points to the "left" hand. After noon, it points to the "right".
Geometry of the natural environment
![Sorts on composing stick](https://upload.wikimedia.org/wikipedia/commons/d/d8/Sorts_on_composing_stick.jpg)
A
right-hand rule
In mathematics and physics, the right-hand rule is a common mnemonic for understanding orientation of axes in three-dimensional space. It is also a convenient method for quickly finding the direction of a cross-product of 2 vectors.
Most of th ...
is one common way to relate three principal directions. For many years a
fundamental question in physics was whether a left-hand rule would be equivalent. Many
natural structures, including human bodies, follow a certain "
handedness
In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more Fine motor skill, dextrous. The other hand, comparatively often the weaker, less dextrous or sim ...
", but it was widely assumed that nature did not distinguish the two possibilities. This changed with the discovery of
parity violations in
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
. If a sample of
cobalt-60
Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisoto ...
atoms
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, an ...
is
magnetize
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
d so that they spin
counterclockwise
Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite ...
around some
axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
*Axis (mathematics), a designator for a Cartesian-coordinate ...
, the
beta radiation
A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β ...
resulting from their
nuclear decay
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
will be preferentially directed opposite that axis. Since counter-clockwise may be defined in terms of up, forward, and right, this experiment unambiguously differentiates left from right using only natural elements: if they were reversed, or the atoms spun
clockwise
Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite ...
, the radiation would follow the spin axis instead of being opposite to it.
Nautical terminology
Bow,
stern
The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Ori ...
,
port, and starboard, fore and aft are nautical terms that convey an impersonal relative direction in the context of the moving frame of persons aboard a ship. The need for impersonal terms is most clearly seen in a rowing shell where the majority of the crew face aft ("backwards"), hence the oars to their right are actually on the port side of the boat. Rowers eschew the terms left, right, port and starboard in favor of stroke-side and bow-side. The usage derives from the tradition of having the stroke (the rower closest to the stern of the boat) oar on the port side of the boat.
Cultures without relative directions
Most human cultures use relative directions for reference, but there are exceptions. Australian Aboriginal peoples like the
Guugu Yimithirr,
Kaiadilt
The Kaiadilt are an Aboriginal Australian people of the South Wellesley group in the Gulf of Carpentaria, Queensland, Australia. They are native to Bentinck Island, but also made nomadic fishing and hunting forays to both Sweers and Allen Is ...
and
Thaayorre
The Thaayorre, or Kuuk Thaayore, are an Australian people living on the southwestern part of the Cape York Peninsula, Queensland in Australia, primarily in the settlement Pormpuraaw, having its foundation in the Edward River Mission.
Languag ...
have no words denoting the egocentric directions in their
language
Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of met ...
; instead, they exclusively refer to
cardinal directions
The four cardinal directions, or cardinal points, are the four main compass directions: north, east, south, and west, commonly denoted by their initials N, E, S, and W respectively. Relative to north, the directions east, south, and west are a ...
, even when describing small-scale spaces. For instance, if they wanted someone to move over on the car seat to make room, they might say "move a bit to the east". To tell someone where exactly they left something in their house, they might say, "I left it on the southern edge of the western table." Or they might warn a person to "look out for that big ant just north of your foot". Other peoples "from
Polynesia
Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...
to
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
and from
Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
to
Bali
Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and Nu ...
" similarly have predominantly "geographic languages".
American Sign Language
American Sign Language (ASL) is a natural language that serves as the predominant sign language of Deaf communities in the United States of America and most of Anglophone Canadians, Anglophone Canada. ASL is a complete and organized visual lang ...
makes heavy use of geographical direction through absolute orientation.
Left-right discrimination and left-right confusion
Left-right discrimination (LRD) refers to a person's ability to differentiate between left and right. The inability to accurately differentiate between left and right is known as left-right confusion (LRC). According to research performed by John R. Clarke of
Drexel University
Drexel University is a private research university with its main campus in Philadelphia, Pennsylvania. Drexel's undergraduate school was founded in 1891 by Anthony J. Drexel, a financier and philanthropist. Founded as Drexel Institute of Art, S ...
, LRC affects approximately 15% of the population. People who have LRC can typically perform daily navigational tasks, such as driving according to road signs or following a map, but may have difficulty performing actions that require a precise understanding of directional commands, such as
ballroom dancing
Ballroom dance is a set of partner dances, which are enjoyed both socially and competitively around the world, mostly because of its performance and entertainment aspects. Ballroom dancing is also widely enjoyed on stage, film, and television.
...
.
Prevalence
Data regarding LRC prevalence is primarily based on behavioral studies, self-assessments, and surveys. Gormley and Brydges found that in a group of 800 adults, 17% of women and 9% of men reported difficulty differentiating between left and right.
Such studies suggest that women are more prone to LRC than men,
with women reporting higher rates of LRC in both accuracy and speed of response.
Sex differences
The Bergen Left-Right Discrimination (BLRD) test is designed to measure individual performance in LRD accuracy. However, this test has been criticized for incorporating tasks that require the use of additional strategies, such as
mental rotation
Mental rotation is the ability to rotate mental representations of two-dimensional and three-dimensional objects as it is related to the visual representation of such rotation within the human mind. There is a relationship between areas of the br ...
(MR).
Because men have been shown to consistently outperform women in MR tasks, tests involving the use of this particular strategy may present alternative cognitive demands and lead to inaccurate assessment of LRD performance.
An extended version of the BLRD test was designed to allow for differential evaluation of LRD and MR abilities, in which subtests were created with either high or low demands on mental rotation. Results from these studies did not find sex differences in LRD performance when mental rotation demands were low.
Another study found that sex differences in left-right discrimination existed in terms of self-reported difficulty, but not in actual tested ability.
Alternatively, studies focused on LRD as a phenomenon distinct from MR concluded that there are sex differences present in LRD.
Scientists controlled for MR demands, potential menstrual cycle effects, and other hormone fluctuations, and determined that the
neurocognitive
Neurocognitive functions are cognitive functions closely linked to the function of particular areas, neural pathways, or cortical networks in the brain, ultimately served by the substrate of the brain's neurological matrix (i.e. at the cellular a ...
mechanisms that support LRD are different for men and women. This research revealed that
inferior parietal
Inferior may refer to:
* Inferiority complex
* An anatomical term of location
* Inferior angle of the scapula, in the human skeleton
* ''Inferior'' (book), by Angela Saini
* ''The Inferior'', a 2007 novel by Peadar Ó Guilín
See also
*Junior (di ...
and right
angular gyrus
The angular gyrus is a region of the brain lying mainly in the posteroinferior region of the parietal lobe, occupying the posterior part of the inferior parietal lobule. It represents the Brodmann area 39.
Its significance is in transferring vis ...
activation were correlated with LRD performance in both men and women. Women also demonstrated increased
prefrontal activation, but did not exhibit greater bilateral activation. Additionally, no correlation was found between LRD accuracy and brain activation, or between brain activation and reaction time, for either sex. These results indicate that there are sex differences in the neurocognitive mechanisms underlying LRD performance; however, findings did not suggest that women are more prone to LRC than men.
Acquisition and comparison
Humans are constantly making decisions about
spatial relation
A spatial relationD. M. Mark and M. J. Egenhofer (1994), "Modeling Spatial Relations Between Lines and Regions: Combining Formal Mathematical Models and Human Subjects Testing"PDF/ref> specifies how some object is located in space in relation to s ...
s; however, some spatial relations, such as left-right, are commonly confused, while other spatial relations, such as up-down, above-below, and front-back, are seldom, if ever, mistaken.
The ability to categorize and compartmentalize space is an essential tool for navigating this 3D world; an ability shown to develop in early infancy.
[
] Infant ability to visually match above-below and left-right relations appears to diminish in early toddlerhood, as language acquisition may complicate verbal labeling. Children learn to verbally discriminate between above-below relations around the age of three, and learn left-right linguistic labels between the ages of six and seven; however, these classifications may only exist in the linguistic context.
In other words, children may learn the terms for left and right without having developed a cognitive representation to allow for the accurate application of such spatial distinctions.
Research seeks to explain the neural activity associated with left-right discrimination, attempting to identify differences in the encoding, consolidation, and retrieval of left-right versus above-below relations. One study found that neural activity patterns for left-right and above-below distinctions are represented differently in the brain, leading to the theory that these spatial judgements are supported by separate cognitive mechanisms.
Experiments used
magnetoencephalography
Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs (su ...
(MEG) to record neural activity during a computerized nonverbal task, examining left-right and above-below differences in
encoding
In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communication ...
and
working memory
Working memory is a cognitive system with a limited capacity that can hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, ...
. Results showed differences in neural activity patterns in the right
cerebellum
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...
, right
superior temporal gyrus
The superior temporal gyrus (STG) is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.
The superior temporal gyrus is bounded by:
* the lat ...
, and left
temporoparietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal and parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus and the limbic system as well ...
during the encoding phase, and indicated differential neural activity in the inferior parietal, right superior temporal, and right cerebellum regions in the working memory tests.
The role of distraction
Although some individuals may struggle with LRD more than others, discriminating between left and right in the face of
distraction
Distraction is the process of diverting the attention of an individual or group from a desired area of focus and thereby blocking or diminishing the reception of desired information. Distraction is caused by: the lack of ability to pay attention ...
has been shown to impair even the most proficient individual's ability to accurately differentiate between the two. This issue is of particular importance to medical students, clinicians and health care professionals, where distraction in the workplace and LRD inaccuracy can lead to severe consequences, including laterality errors and wrong-side surgeries.
Laterality errors in the field of
aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
may also lead to equally devastating results, for example, causing a major airline crash.
Distraction has a significant impact on LRD accuracy, and the type of distraction can alter the magnitude of these effects. For example, cognitive distraction, which occurs when an individual is not directly focused on the task at hand, has a more profound effect on LRD performance than auditory distraction, such as the presence of continuous
ambient noise
Background noise or ambient noise is any sound other than the sound being monitored (primary sound). Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise levels.
Background no ...
.
Additionally, in the field of health care, it has been noted that mental rotation is often involved in making left-right distinctions, such as when a medical practitioner is facing their patient and must adjust for the opposite left-right relations.
See also
*
Anatomical terms of location
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
*
Cardinal direction
The four cardinal directions, or cardinal points, are the four main compass directions: north, east, south, and west, commonly denoted by their initials N, E, S, and W respectively. Relative to north, the directions east, south, and west are at ...
*
Cerebral hemisphere
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...
*
Clock position
A clock position, or clock bearing, is the direction of an object observed from a vehicle, typically a vessel or an aircraft, relative to the orientation of the vehicle to the observer. The vehicle must be considered to have a front, a back, a ...
*
Dexter and sinister
''Dexter'' and ''sinister'' are terms used in heraldry to refer to specific locations in an escutcheon bearing a coat of arms, and to the other elements of an achievement. ''Dexter'' (Latin for 'right') indicates the right-hand side of the sh ...
*
Direction determination Direction determination refers to the ways in which a cardinal direction or compass point can be determined in navigation and wayfinding. The most direct method is using a compass (magnetic compass or gyrocompass), but indirect methods exist, based ...
*
Horizontal direction
In astronomy, geography, and related sciences and contexts, a '' direction'' or ''plane'' passing by a given point is said to be vertical if it contains the local gravity direction at that point.
Conversely, a direction or plane is said to be hor ...
*
Dextral and sinistral
*
Handedness
In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more Fine motor skill, dextrous. The other hand, comparatively often the weaker, less dextrous or sim ...
*
List of international common standards
A list of international common and basic technical standards, which have been established worldwide and are related by their frequent and widespread use. These standards are conventionally accepted as best practice and used globally by industry an ...
*
Orientation (geometry)
In geometry, the orientation, angular position, attitude, bearing, or direction of an object such as a line, plane or rigid body is part of the description of how it is placed in the space it occupies.
More specifically, it refers to the imagin ...
*
Port and starboard
Port and starboard are nautical terms for watercraft and aircraft, referring respectively to the left and right sides of the vessel, when aboard and facing the bow (front).
Vessels with bilateral symmetry have left and right halves which are ...
*
Rotation
Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...
*
Sense of direction
Sense of direction is the ability to know one's location and perform wayfinding. It is related to cognitive maps, spatial awareness, and spatial cognition.
Sense of direction can be impaired by brain damage, such as in the case of topographical di ...
*
Slant direction
In radio electronics, especially radar terminology, slant range or slant distance is the distance along the relative direction between two points. If the two points are at the same level (relative to a specific datum), the slant distance equals ...
*
Topographical disorientation
Topographical disorientation is the inability to orient oneself in one's surroundings, sometimes as a result of focal brain damage. This disability may result from the inability to make use of selective spatial information (e.g., environmental l ...
*
Visuospatial dysgnosia
*
Windward and leeward
Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
References
{{DEFAULTSORT:Relative Direction
Orientation (geometry)