Peripheral vision
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2008-07-03T20:37:42Z
Hans-Werner34
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'''Peripheral vision''' is a part of [[visual perception|vision]] that occurs outside the very center of gaze. There is a broad set of non-central points in the [[field of view]] that is included in the notion of peripheral vision. "Far peripheral" vision exists at the edges of the field of view, "mid-peripheral" vision exists in the middle of the field of view, and "near-peripheral", sometimes referred to as "paracentral" vision, exists adjacent to the center of gaze{{Fact|date=February 2007}}.
Peripheral vision is weaker in [[human]]s, compared with other animals, especially at distinguishing [[color vision|color]] and shape. This is because the density of receptor cells on the [[retina]] is greatest at the center and lowest at the edges (see [[visual system]] for an explanation of these concepts). In addition, there are two types of receptor cells, [[rod cell]]s and [[cone cell]]s; rod cells are unable to distinguish color and are predominant at the periphery, while cone cells are concentrated mostly in the center of the retina, the [[fovea]].
[[Image:Double_system_E.jpg|thumb|300px|right]]
[[Flicker fusion threshold]] is higher for peripheral than [[fovea]]l vision. Peripheral vision is good at detecting motion (a feature of rod cells), and is relatively strong at night or in the dark, when the lack of color cues and lighting makes cone cells far less useful. This makes it useful for avoiding predators, who tend to hunt at night and may attack unexpectedly.
Peripheral vision loss results in [[tunnel vision]] .
The distinctions between [[foveal ]](sometimes also called central) and peripheral vision are reflected in subtle physiological and anatomical differences in the [[visual cortex]]. Different visual areas contribute to the processing of visual information coming from different parts of the visual field, and a complex of visual areas located along the banks of the interhemispheric fissure (a deep groove that separates the two brain hemispheres) has been linked to peripheral vision. It has been suggested that these areas are important for fast reactions to visual stimuli in the periphery, and monitoring body position relative to gravity <ref name="PalmerRosa2006">{{cite journal | author=Palmer SM, Rosa MG | year=2006 | title=A distinct anatomical network of cortical areas for analysis of motion in far peripheral vision | journal=Eur J Neurosci | volume=24(8) |pages=2389–405 | doi=10.1111/j.1460-9568.2006.05113.x}}</ref>It is used to see dangers coming up besides you.
[[Image: Eye_movements_of_a_chess_champion_nc.jpg |thumb|400px| left |Ovals A, B and C show which portions of the chess situation a chess master can reproduce correctly with his peripheral vision. Lines show path of foveal fixation during 5 seconds when the task is to memorize the situation as correctly as possible.Image from <ref>Hans-Werner Hunziker, (2006) Im Auge des Lesers: foveale und periphere Wahrnehmung - vom Buchstabieren zur Lesefreude [In the eye of the reader: foveal and peripheral perception - from letter recognition to the joy of reading] Transmedia Stäubli Verlag Zürich 2006 ISBN 978-3-7266-0068-6</ref> based on data by <ref> DE GROOT, A. : Perception and memory in chess; an experimental study of the heuristics of the professional eye. Mimeograph; Psychologisch Laboratorium Universität van Amsterdam, Seminarium September 1969</ref>]]
The main functions of peripheral vision<ref>Hans-Werner Hunziker, (2006) Im Auge des Lesers: foveale und periphere Wahrnehmung - vom Buchstabieren zur Lesefreude [In the eye of the reader: foveal and peripheral perception - from letter recognition to the joy of reading] Transmedia Stäubli Verlag Zürich 2006 ISBN 978-3-7266-0068-6</ref> are:
* recognition of well-known structures and forms with no need to focus by the foveal line of sight.
* identification of similar forms and movements ([[Gestalt psychology]] laws)
* delivery of sensations which form the background of detailed visual perception.
== References ==
<references/>
==See also==
*[[Averted vision]]
* [[Perimetry]]
* [[Visual field]]
* [[Vision span]]
* [[Visual perception]]
* [[Fovea]]
* [[Eye movement]]
* [[Eye movement in language reading]]
* [[Eye movement in music reading]]
[[Category:Vision]]