In philosophy, psychology, and cognitive science, perception is the process of attaining awareness or understanding of sensory information. The word "perception" comes from the Latin words perceptio, percipio, and means "receiving, collecting, action of taking possession, apprehension with the mind or senses."
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.
What one perceives is a result of interplays between past experiences, including oneÕs culture, and the interpretation of the perceived.
Two types of consciousness are considerable regarding perception: phenomenal (any occurrence that is observable and physical) and psychological. The difference every sighted person can demonstrate to him- or herself is by the simple opening and closing of his or her eyes: phenomenal consciousness is thought, on average, to be predominately absent without senses such as sight. Through the full or rich sensations present in senses such as sight, nothing by comparison is present while the senses are not engaged, such as when the eyes are closed. Using this precept, it is understood that, in the vast majority of cases, logical solutions are reached through simple human sensation. The analogy of Plato's Cave was coined to express these ideas.
Passive perception (conceived by Renˇ Descartes) can 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, which is increasingly gaining experimental support, can be surmised as dynamic relationship between "description" (in the brain) <-> senses <-> surrounding, all of which holds true to the linear concept of experience.
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. The question, "Is the glass half empty or half full?" serves to demonstrate the way an object can be perceived in different ways.
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 concept about it, they tend to take those concepts 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.
A personÕs knowledge creates his or her reality as much as the truth, because the human mind can only contemplate that to which it has been exposed. 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 donÕt comprehend.
This confusing ambiguity of perception is exploited in human technologies such as camouflage, and also in biological mimicry, for example by European 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.[6]
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.
Preconceptions can influence how the world is perceived. For example, one classic psychological experiment showed slower reaction times and less accurate answers when a deck of playing cards reversed the color of the suit symbol for some cards (e.g. red spades and black hearts).
There is also evidence that the brain in some ways operates on a slight "delay", to allow nerve impulses from distant parts of the body to be integrated into simultaneous signals.
An ecological understanding of perception derived from Gibson's early work is that of "perception-in-action", the notion that perception is a requisite property of animate action; that without perception action would be unguided, and without action perception would serve no purpose. Animate actions require both perception and motion, and perception and movement can be described as "two sides of the same coin, the coin is action".
Gibson works from the assumption that singular entities, which he calls "invariants", already exist in the real world and that all that the perception process does is to home in upon them. A view known as constructivism (held by such philosophers as Ernst von Glasersfeld) regards the continual adjustment of perception and action to the external input as precisely what constitutes the "entity", which is therefore far from being invariant.
Glasersfeld considers an "invariant" as a target to be homed in upon, and a pragmatic necessity to allow an initial measure of understanding to be established prior to the updating that a statement aims to achieve. The invariant does not and need not represent an actuality, and Glasersfeld describes it as extremely unlikely that what is desired or feared by an organism will never suffer change as time goes on. This social constructionist theory thus allows for a needful evolutionary adjustment.
A mathematical theory of perception-in-action has been devised and investigated in many forms of controlled movement, and has been described in many different species of organism using the General Tau Theory. According to this theory, tau information, or time-to-goal information is the fundamental 'percept' in perception.
Empirical Theories of Perception Wikipedia
Remembrance of things future: Long-term memory sets the stage for visual perception PhysOrg - December 28, 2011
Rather than being a passive state, perception is an active process fueled by predictions and expectations about our environment. In the latter case, memory must be a fundamental component in the way our brain generates these precursors to the perceptual experience Š but how the brain integrates long-term memory with perception has not been determined.
Time on the Brain: How You Are Always Living In the Past, and Other Quirks of Perception Scientific American - September 20, 2011
Neuroscientist Kathleen McDermott of Washington University began by quoting famous memory researcher Endel Tulving, who called our ability to remember the past and to anticipate the future mental time travel. You donÕt use the phrase time travel lightly in front of a group of physicists for whom the concept is not a convenient metaphor but a very real possibility. But when you hear about how our minds glide through time - and how our memory provides a link not only to the past but also to the future - you see TulvingÕs point.
Sad People Have Surprising Memory Advantage Live Science - August 21, 2011
Sad people are apparently better than happy people at face recognition, an upside to being down in the dumps that is yielding insights into how mood can affect the brain. The findings, based on experiments involving college students, could help lead to better treatments for depression, psychologists say. Past studies have found that unhappiness is often detrimental to a wide range of mental tasks, such as abstract thinking and remembering lists of words. A number of researchers had attributed this to brooding deeply and elaborately about one's surroundings, while others thought it might be due to being distracted by one's own concerns.
Cognitive neuroscientists shed light on how the brain responds to scenes and their mirror-image reversals PhysOrg - August 18, 2011
New research suggests that some parts of the brain perceive a scene and its mirror image as one and the same, meaning those regions are involved in scene categorization rather than navigation. Picture a penny. You can probably recall its color (copper), which historical figure graces its front (Abraham Lincoln), and even the orientation of the portrait (profile, as opposed to straight on). But can you remember which way Lincoln is facing? According to MIT research scientist Daniel D. Dilks, only about half of us get this right, meaning weÕre performing no better than if we had simply guessed. This well-known phenomenon suggests that left-right distinctions are irrelevant to object recognition; in other words, our brains perceive an object and its mirror image as one and the same.
Illusion Reveals How Brain Adapts to Motion Live Science - July 1, 2011
Watch something in motion, say, a waterfall or scrolling text on a video game, then look away at a rock, a wall, or anything stationary. Briefly, the stationary object will appear to move in the opposite direction. This visual illusion has been recognized for a very long time; Aristotle first noted it. Now, a new study has found that even a very brief glimpse of motion - for as little as 1/40 of a second - can trigger the brain mechanism responsible for the illusion.
Missing the gorilla: Why we don't see what's right in front of our eyes PhysOrg - April 18, 2011
University of Utah psychologist Jason Watson displays a famous video showing people passing a basketball while a person in a gorilla suit walks across the screen. When unsuspecting viewers were asked to count how many times the basketball is passed, more than 40 percent failed to see the person in the gorilla suit.
World's Oldest Optical Illusion Found? National Geographic - December 24, 2010
Long before the famous duck-rabbit illusion, prehistoric artists were creating mind-bending double images of their own, according to a new paper presented earlier this year at an international convention on rock art research.
Scientists find evidence for 'chronesthesia,' or mental time travel PhysOrg - December 22, 2010
Researchers have found evidence for chronesthesia, which is the brainÕs ability to be aware of the past and future, and to mentally travel in subjective time. They found that activity in different brain regions is related to chronesthetic states when a person thinks about the same content during the past, present, or future.
New study debunks myth about popular optical illusion PhysOrg - December 21, 2010
A psychology professor has found that the way people perceive the Silhouette Illusion, a popular illusion that went viral and has received substantial online attention, has little to do with the viewers' personality, or whether they are left- or right-brained, despite the fact that the illusion is often used to test these attributes in popular e-quizzes.
How the brain's architecture makes our view of the world unique PhysOrg - December 6, 2010
The Ebbinghaus Illusion. Most people will see the first circle as smaller than the second one Researchers found a strong link between the surface area of the primary visual cortex and the extent to which volunteers perceived the size illusion -- the smaller the area, the more pronounced the visual illusion.
Now You See It: Neuroscientists Reveal Magicians' Secrets Live Science - December 6, 2010
Magicians create illusions by taking advantage of how we perceive stimuli and process information. For example, a dove fluttering from a hat can be used to draw an audience's attention away from the actual trick. There is a place for magic in science. Five years ago, on a trip to Las Vegas, neuroscientists Stephen Macknik and Susana Martinez-Conde realized that a partnership was in order with a profession that has an older and more intuitive understanding of how the human brain works. Magicians, it seems, have an advantage over neuroscientists.
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