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Visual perception is the end product of vision, consisting of the ability to detect light and interpret (see) the consequences of light stimuli. The resulting perception is known as eyesight, sight or vision. Vision has a specific sensory system, the visual system. The visual system
Photochemistry of vision In the vision system, retinal, technically called retinene1 or "retinaldehyde", is a light-sensitive retinene molecule found in the photoreceptor cells of the retina. Retinal is the fundamental structure involved in the transduction of light into visual signals, i.e. nerve impulses, in occular system of the central nervous system. In the presence of light, the retinal molecule changes configuration and as a result a nerve impulse is generated. Theoretical perspectives in the study of visual perception The major problem in visual perception is that what people see is not simply a translation of retinal stimuli (i.e., the image on the retina). Thus people interested in perception have long struggled to explain what visual processing does to create what we actually see. Unconscious inference Hermann von Helmholtz is often credited with the founding of the scientific study of visual perception. Helmholtz held vision to be a form of unconscious inference: vision is a matter of deriving a probable interpretation for incomplete data. Inference requires prior assumptions about the world: two well-known assumptions that we make in processing visual information are that light comes from above, and that objects are viewed from above and not below. The study of visual illusions (cases when the inference process goes wrong) has yielded a lot of insight into what sort of assumptions the visual system makes. The unconscious inference hypothesis has recently been revived in so-called Bayesian studies of visual perception. Proponents of this approach consider that the visual system performs some form of Bayesian inference to derive a perception from sensory data. Models based on this idea have been used to describe various visual subsystems, such as the perception of motion or the perception of depth. An introduction can be found in Mamassian, Landy & Maloney (2002). See here * for a non-mathematical tutorial on these general ideas. Gestalt theory Gestalt psychologists working primarily in the 1930s and 1940s raised many of the research questions that are studied by vision scientists today. The Gestalt Laws of Organization have guided the study of how people perceive visual components as organized patterns or wholes, instead of many separate parts. Gestalt is a German word that translates to "configuration or pattern". According to this theory, there are six main factors that determine how we group things according to visual perception. It has also been shown that certain individual differences such as impairment of sight and spatial skills can also affect our visual perception. There are also other factors that influence how we perceive things such as personality, cognitive styles, gender, occupation, age, values, attitudes, motivation, beliefs, etc. Ecological psychology Psychologist James J. Gibson developed a theoretical perspective on sensory perception called Ecological psychology that is radically different from that of Helmholtz. Gibson considers that enough visual perception is available in normal environments to allow for veridical perception (accurate perception of the world). Gibson replaces inference with information pickup. Although most researchers today feel closer to Helmholtz's unconscious inference theory, Gibson has done much in identifying what sort of information is available to the visual system. See also Types of visual perception Disorders/Dysfunctions Related Disciplines Other | |||||||||
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