Haptic perception ( "palpable", ''haptikόs'' "suitable for touch") means literally the ability "to grasp something", and is also known as stereognosis.

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 syste ...

in this case is achieved through the active exploration of surfaces and objects by a moving subject, as opposed to passive contact by a static subject during ''tactile perception''.Weber, E. H. (1851). ''Die Lehre vom Tastsinne und Gemeingefühle auf Versuche gegründet''. Friedrich Vieweg und Sohn. Haptic perception involves the

cutaneous receptor A cutaneous receptor is a sensory receptor found in the skin that provides information about temperature, touch (including vibration and pain), spatial orientation,pressure (stretching or squeezing), and metabolic circumstances (including those i ...

s of

touch The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of bo ...

, and proprioceptors that sense movement and body position. The inability for haptic perception is known as astereognosis.

History

The term ''haptik'' was coined by the German Psychologist Max Dessoir in 1892, when suggesting a name for academic research into the sense of touch in the style of that in "acoustics" and "optics". Gibson (1966) defined the haptic system as " e sensibility of the individual to the world adjacent to his body by use of his body". Gibson and others further emphasized what Weber had realized in 1851: the close interdependence of haptic perception and body movement, and that haptic perception is active exploration. The concept of haptic perception is related to the concept of extended physiological proprioception, according to which when a tool such as a stick is used, perceptual experience is transparently transferred to the end of the tool. Haptic perception relies on the forces experienced during touch. This research allows the creation of "virtual", illusory haptic shapes with different perceived qualities, which has clear application in

haptic technology Haptic technology (also kinaesthetic communication or 3D touch) is technology that can create an experience of touch by applying forces, vibrations, or motions to the user. These technologies can be used to create virtual objects in a computer s ...

Exploratory procedures

People can rapidly and accurately identify three-dimensional objects by touch. They do so through the use of exploratory procedures, such as moving the fingers over the outer surface of the object or holding the entire object in the hand. The following exploratory procedures have been identified so far: #Lateral motion #Pressure #Enclosure #Contour following Thus gathered object or subject properties are size, weight, contour, surface and material characteristics, consistency and temperature. Along with the development of tactile sensors, some work has also been dedicated to developing exploratory behavior in robots.

Perceptual deadband

Perceptual deadband is a region which captures perceptual limitations of human perception. The Weber fraction and the level crossings constant are employed to define the perceptual deadband for haptic force stimulus. The deadband has an important application in designing perceptually adaptive sampling mechanisms for haptic data compression, which is required for transmitting haptic data over a communication network. There are many factors which affect the possible shapes of the perceptual deadband, for example: # Rate of change of force stimulus: The Weber fraction or level crossings constant decrease for a faster change in the force stimulus. # Temporal resolution: It is defined as the minimum time spacing required in perceiving two consecutive force samples. # Directional sensitivity: The study claims that the Weber fraction is a function of only the force magnitude, not the direction. # Task being performed: discriminative or comparative A user is more sensitive while doing a comparative task than a discriminative task. It is because one has to perceive changes only along one direction under the comparative task. All this signifies that the perceptual deadband is a function of the task to be carried out.

Impairments of haptic sensitivity

Exo-Skin Soft Haptic exoskeletal interface DSCF2171

Haptic sensitivity can be impaired by a multitude of diseases and disorders, predominantly relating to

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

injuries such as cuts and burns, and

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

lesions (through injury or impaired circulation). Additionally, loss of sensitivity (

neuropathy Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropa ...

) may be caused by

metabolic Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the ...

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

and/or immunologic factors. Examples of medical conditions that can cause neuropathies are

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

chronic kidney disease Chronic kidney disease (CKD) is a type of long-term kidney disease, defined by the sustained presence of abnormal kidney function and/or abnormal kidney structure. To meet criteria for CKD, the abnormalities must be present for at least three mo ...

, thyroid dysfunction (hyper- and

hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...

) as well as

hepatitis Hepatitis is inflammation of the liver parenchyma, liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), Anorexia (symptom), poor appetite ...

liver cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, chronic liver failure or chronic hepatic failure and end-stage liver disease, is a chronic condition of the liver in which the normal functioning tissue, or parenchyma, is replaced ...

and alcohol dependency.

Autism Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing d ...

sensory processing disorder Sensory processing disorder (SPD), formerly known as sensory integration dysfunction, is a condition in which multisensory input is not adequately processed in order to provide appropriate responses to the demands of the environment. Sensory ...

, etc. can also affect haptic sensitivity. Loss of the sense of touch is a catastrophic deficit that can impair walking and other skilled actions such as holding objects or using tools.

Haptic therapy

Immersive environments can recreate the feeling of haptic interaction. Exoskeletal gloves such as the Exo-Skin Soft Haptic exoskeletal interface, developed at

Drexel University Drexel University is a private university, private research university with its main campus in Philadelphia, Pennsylvania, United States. Drexel's undergraduate school was founded in 1891 by Anthony Joseph Drexel, Anthony J. Drexel, a financier ...

, can be programmed to take a patient through a program of physical therapy exercises to retrain muscles and senses.

History

Exploratory procedures

Perceptual deadband

Impairments of haptic sensitivity

Haptic therapy

See also

References

Further reading