In
psychology and the
cognitive sciences, 'perception' is the process of acquiring, interpreting, selecting, and organizing
sensory information. It is a task far more complex than was imagined in the 1950s and 1960s, when it was proclaimed that building perceiving machines would take about a decade, but, needless to say, that is still very far from reality. The word ''perception'' comes from the Latin ''perception-, percepio, '', meaning "receiving, collecting, action of taking possession, apprehension with the mind or senses." --OED.com. Methods of studying perception range from essentially
biological or
physiological approaches, through
psychological approaches through the
philosophy of mind and in
empiricist epistemology, such as that of
David Hume,
John Locke,
George Berkeley, or as in
Merleau Ponty's affirmation of perception as the basis of all science and
There are two basic theories of perception: Passive Perception (PP) and Active Perception (PA). The passive perception (conceived with
René Descartes) is addressed in this article and could be surmised as the following sequence of events: surrounding - > input (senses) - > processing (brain) - > output (re-action). Although still supported by mainstream philosophers, psychologists and neurologists, this theory is nowadays losing momentum. The theory of active perception has emerged from extensive research of sensory illusions with works of
Professor Emeritus Richard L Gregory in a lead. This theory is increasingly gaining experimental support and could be surmised as dynamic relationship between “description” (in the brain) < - > senses < - > surrounding.
History of the study of perception
Perception is one of the oldest fields within scientific psychology, and there are correspondingly many theories about its underlying processes. The oldest quantitative law in psychology is the
Weber-Fechner law, which quantifies the relationship between the intensity of physical stimuli and their perceptual effects. It was the study of perception that gave rise to the
Gestalt school of psychology, with its emphasis on
holistic approach. .
Perception and reality

Ambiguous images
Many
cognitive psychologists hold that, as we move about in the world, we create a
model of how the world works. That is, we sense the objective world, but our sensations map to
percepts, and these percepts are provisional, in the same sense that scientific hypotheses are provisional (cf. in the
scientific method).
As we acquire new
information, our percepts shift, thus solidifying the idea that perception is a matter of belief.
Abraham Pais' biography refers to the 'esemplastic' nature of
imagination. In the case of visual perception, some people can actually see the percept shift in their
mind's eye. Others who are not
picture thinkers, may not necessarily perceive the 'shape-shifting' as their world changes. The 'esemplastic' nature has been shown by experiment: an
ambiguous image has multiple interpretations on the perceptual level.
Just as one object can give rise to multiple percepts, so an object may fail to give rise to any percept at all: if the percept has no grounding in a person's experience, the person may literally not perceive it.
This confusing
ambiguity of perception is exploited in human technologies such as
camouflage, and also in biological
mimicry, for example by
Peacock butterflies, whose wings bear eye markings that birds respond to as though they were the eyes of a dangerous
predator. Perceptual ambiguity is not restricted to vision. For example, recent
touch perception research (
Robles-De-La-Torre & Hayward 2001) found that
kinesthesia-based
haptic perception strongly relies on the forces experienced during touch. This makes it possible to produce
illusory touch percepts (see also the MIT Technology Review article
The Cutting Edge of Haptics).
Cognitive theories of perception assume there is a
poverty of stimulus. This (with reference to perception) is the claim that
sensations are, by themselves, unable to provide a unique description of the world.
Sensations require 'enriching', which is the role of the mental
model. A different type of theory is the
perceptual ecology approach of
James J. Gibson. Gibson rejected the assumption of a
poverty of stimulus by rejecting the notion that perception is based in sensations. Instead, he investigated what information is actually presented to the perceptual systems. He (and
the psychologists who work within this
paradigm) detailed how the world could be specified to a mobile, exploring organism via the lawful projection of information about the world into energy arrays. Specification is a 1:1 mapping of some aspect of the world into a perceptual array; given such a mapping, no enrichment is required and perception is
direct.
Perception-in-Action
The ecological understanding of perception advanced from Gibson's early work is perception-in-action, the notion that perception is a requisite property of animate action, without perception action would not be guided and without action perception would be pointless. Animate actions require perceiving and moving together. In a sense, "perception and movement are two sides of the same coin, the coin is action."
(D.N. Lee) A mathematical theory of perception-in-action has been devised and investigated in many forms of controlled movement by many different species of organism,
General Tau Theory. According to this theory, tau information, or time-to-goal information is the fundamental 'percept' in perception.-
Perception and action
We gather information about the world and interact with it through our actions. Perceptual information is critical for action. Perceptual deficits may lead to profound deficits in action (for touch-perception-related deficits, see
Robles-De-La-Torre 2006).
Types of perception
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Amodal perception
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Color perception
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Depth perception
★ Form perception
★ Haptic perception
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Speech perception
★ Perception as Interpretation
★ Numeric Value of Perception
★ Perceive
References and Further Reading
★ Flanagan, J.R., Lederman, S.J.
Neurobiology: Feeling bumps and holes, News and Views, Nature, 412(6845):389-91 (2001).
★
James.J.Gibson, ''The Senses Considered as Perceptual Systems''. Boston 1966.
★ James J. Gibson. ''The Ecological Approach to Visual Perception''. Lawrence Erlbaum Associates, 1987. ISBN 0898599598
★ Hayward V, Astley OR, Cruz-Hernandez M, Grant D, Robles-De-La-Torre G.
Haptic interfaces and devices. Sensor Review 24(1), pp. 16-29 (2004).
★ Robles-De-La-Torre G. & Hayward V.
Force Can Overcome Object Geometry In the perception of Shape Through Active Touch. Nature 412 (6845):445-8 (2001).
★ Robles-De-La-Torre G.
The Importance of the Sense of Touch in Virtual and Real Environments. IEEE Multimedia 13(3), Special issue on Haptic User Interfaces for Multimedia Systems, pp. 24-30 (2006).
External links
★
Online papers on perception, by various authors, compiled by
David Chalmers
★
Paradoxical haptic objects. An example of touch illusions of shape. See also the MIT Technology Review article:
★
The Cutting Edge of Haptics, by Duncan Graham-Rowe.
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Theories of Perception
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Richard L Gregory
See also
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Apophenia
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Autopoiesis
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Pareidolia
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Philosophy of perception
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Psychophysics
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Sensory Neuroscience
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Visual routine
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Illusion
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Deregowski's Cross-Cultural Study on Perception
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Perceptual constancy