Peripheral vision

Peripheral vision

Peripheral vision is a part of 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 gazeFact|date=February 2007.

Peripheral vision is weaker in humans, compared with other animals, especially at distinguishing 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 cells and cone cells; 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.

Flicker fusion threshold is higher for peripheral than foveal 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 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] It is used to see dangers coming up besides you.

The main functions of peripheral vision [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] 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

ee also

*Averted vision
* Perimetry
* Visual field
* Vision span
* Visual perception
* Fovea
* Eye movement
* Eye movement in language reading
* Eye movement in music reading


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