The autokinetic effect is an optical illusion. It occurs when a perceiver staring at a stationary pinpoint of light in an otherwise completely dark visual field believes that the light moves from its fixed position. This “self-motion” (auto-kinetic) is caused, in part, by the nearly imperceptible movements of the eye known as saccades. Ordinarily the visual system compensates for these naturally occurring motions of the eye, but when only a single light is visible with no frame of reference, the light appears to wander in unpredictable directions and at variable speeds. This illusion was first noted by astronomers when viewing a single star on a very dark night.

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Copyright © 2008 Macmillan Reference USA. This book chapter first appeared in International Encyclopedia of the Social Sciences.

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