Peripheral vision

Peripheral vision is a form of visual perception, in which not the central part of the retina ( fovea ) is used for fixing an object, but their perception is done by next location ( extrafoveal ) areas. De facto, therefore, looks over an observer to the object. In contrast to foveal vision, in which the line of sight of the eye is aligned exactly on the desired object, to achieve maximum visual acuity, peripheral vision, although it is only an imprecise and optically distorted visual impressions outside of a solid fixation point. By interconnection of photoreceptor cells as groups but a sampling is achieved for up to 100 per second, instead of only 3 to 4 as in foveal vision.

The perceived by peripheral vision points do not correspond to the peripheral visual field. This is determined on a calm head and body posture, and straight directional views. In contrast, allows peripheral vision eye and head movements to turn on the desired object.

Peripheral vision is very efficient for the perception of motion and because of its mainly for light-dark -sensitive rods of the retina periphery even at extremely low brightness of benefits, such as seeing at night. It can not support the perception of color variations, so for example, conspicuous traffic signals are flashing and / or / shown with contrasting colors such as black yellow.

Its temporal resolution is highest in the extreme periphery, which you can easily spot when you look at the bright image of an older tube TV completely out of the corner of my eye. The flickering is then much more noticeable than in the direct viewing the image. ( Newer flat screens are suitable for this demonstration is not. )

So Peripheral vision provides an overall impression of a situation where the - is a more detailed analysis by the foveal system - if it is not classified as dangerous immediately.

Although the peripheral system covers more than 99.9 % of the visual field, are for his information only about 50% of the optic nerve as well as about 50 % of the area of the visual cortex (visual cortex ) are available. The remaining 50 % is reserved for high-definition but very slow foveal system.

The oval areas A, B and C show the parts of a chess situation, a chess master from the periphery - correctly recognize - that fix directly without it. The lines show the path of the eye fixations for 5 seconds when you had to try to memorize the position of the individual figures. Image out of based on data.

Applications

Persons with a central scotoma, such as macular degeneration, often use peripheral retina in order, even if only very blurred looking at things, that could no longer recognize with central fixation. In ophthalmology, this phenomenon is called eccentric setting.

Peripheral vision is known in astronomy as averted vision and refers to a special technique to very faint stars and areal objects to recognize (fog) better. This one is not looking directly past the sky object, but short of it.