What Is Integrated Across Fixations?

Abstract

Our strongest introspection in perception is of a stable world. However, the visual system obtains an input that is far from stable. In normal viewing conditions--when the eye in not tracking a moving object--the eyes stay relatively immobile for periods of only a fraction of a second. In between these periods of rest (called fixations), there are rapid ballistic eye movements (called saccades) in which the retinal image is merely a smear. Thus, vision usually consists of the following sequence of events: an interval of a sixth to about a half a second in which there is a stable retinal image followed by a brief interval of a smear, an interval with a different stable retinal image, another smear, and so on (Rayner, 1978a). A central question of visual perception is how the precept of a stable world emerges from all this chaos.