Function
Humans and many other animals do not look at a scene in fixed steadiness (as opposed to most birds, for example); instead, the eyes move around, locating interesting parts of the scene and building up a mental, three-dimensional 'map' corresponding to the scene (as opposed to the graphical map of avians, that often relies upon detection of angular movement on the retina). When scanning the scene in front of you or reading these words right now, your eyes make jerky saccadic movements and your eyes stop several times, moving very quickly between each stop. We can not consciously control the speed of movement between stops and during each saccade; the eyes move as fast as they can. One reason for the saccadic movement of the human eye is that the central part of the retina—known as the fovea—plays a critical role in resolving objects. By moving the eye so that small parts of a scene can be sensed with greater resolution, body resources can be used more efficiently.
Read more about this topic: Saccade
Famous quotes containing the word function:
“The fact remains that the human being in early childhood learns to consider one or the other aspect of bodily function as evil, shameful, or unsafe. There is not a culture which does not use a combination of these devils to develop, by way of counterpoint, its own style of faith, pride, certainty, and initiative.”
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