Perception

Neuropsychology
Topics
Brain-computer interface Traumatic brain injury Brain regions • Clinical neuropsychology Cognitive neuroscience • Human brain Neuroanatomy • Neurophysiology Phrenology • Common misconceptions
Brain functions
arousal • attention consciousness • decision making executive functions • natural language learning • memory motor coordination • sensory perception planning • problem solving • thought
People
Arthur L. Benton • David Bohm António Damásio • Phineas Gage Norman Geschwind • Elkhonon Goldberg Donald O. Hebb • Kenneth Heilman Edith Kaplan • Muriel Lezak Benjamin Libet • Rodolfo Llinás Alexander Luria • Brenda Milner Karl H. Pribram • Oliver Sacks Roger W. Sperry • H. M. • K. C.
Tests
Bender-Gestalt Test Benton Visual Retention Test Clinical Dementia Rating Continuous Performance Task Glasgow Coma Scale Hayling and Brixton tests Johari window • Lexical decision task Mini-mental state examination Stroop effect Wechsler Adult Intelligence Scale Wisconsin card sorting
Mind and Brain Portal

In psychology and the cognitive sciences, perception is the process of attaining awareness or understanding of sensory information. It is a task far more complex than was imagined in the 1950s and 1960s, when it was predicted that building perceiving machines would take about a decade, a goal which is still very far from fruition. The word perception comes from the Latin words perception, percepio, meaning "receiving, collecting, action of taking possession, apprehension with the mind or senses."^[1]

What one perceives is a result of interplays between past experiences, one’s culture and the interpretation of the perceived. If the percept does not have support in any of these perceptual bases it is unlikely to rise above perceptual threshold.

Perception gives rise to two types of consciousness: phenomenal and psychological. The difference everybody can demonstrate to himself/herself by simple opening and closing his/her eyes. Phenomenal consciousness is full of rich sensations that are hardly present when eyes are closed. Psychological consciousness is well researched and measured. It occurs half a second after a stimulus starts. If a weak stimulus lasts less, it is unlikely to be perceived. The capacity of psychological consciousness is also well measured. Depending on methods used the capacity ranges between seven and forty symbols or percepts at one time.

There are two basic theories of perception: Passive Perception (PP) and Active Perception (PA). The passive perception (conceived by 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, most notably the works of Richard L. Gregory. This theory is increasingly gaining experimental support and could be surmised as dynamic relationship between “description” (in the brain) ↔ senses ↔ surrounding.

Perception is one of the oldest fields in psychology. 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. The study of perception gave rise to the Gestalt school of psychology, with its emphasis on holistic approach.

Contents 1 Perception and reality 2 Perception-in-action 3 Types of perception 4 References and further reading 5 See also 6 External links

Perception and reality

In the case of visual perception, some people can actually see the precept shift in their mind's eye. Others who are not , 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.

The processes of perception routinely alter what humans see. When people view something with a preconceived idea about it, they tend to take those preconceived ideas and see them whether or not they are there. This problem stems from the fact that humans are unable to understand new information, without the inherent bias of their previous knowledge. The extent of a person’s knowledge creates their reality as much as the truth, because the human mind can only contemplate that which it has been exposed to. When objects are viewed without understanding, the mind will try to reach for something that it already recognizes, in order to process what it is viewing. That which most closely relates to the unfamiliar from our past experiences, makes up what we see when we look at things that we don’t comprehend.

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. ^[2]

Cognitive theories of perception assume there is a poverty of stimulus. This (with reference to perception) is the claim that sensation 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 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.

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." 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.-

Types of perception

• a.) Amodal perception
• b.) Color perception
• c.) Depth perception
• d.) Visual perception
• e.) Form perception
• f.) Haptic perception
• g.) Speech perception
• h.) Perception as Interpretation
• i.) Numeric Value of Perception
• j.) Pitch perception
• k.) Harmonic perception
• l.) Rhythmic perception.

References and further reading

See also

External links

• 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.
• Theories of Perception
• Richard L Gregory