EVIDENCE FOR THE PERSISTENCE OF VISUAL GUIDANCE INFORMATION

An earlier study from our laboratory provided initial support for the hypothesis that information facilitating visual guidance persists in t he absence of retinal stimulation. The present study supports and exte nds this hypothesis with three experiments in which visually occluded subjects positioned a point of light at the location of a previously v iewed target and also walked in the direction of a previously viewed p ath. In both tasks, performance was possible following occlusion, and in all cases, performance slowly and significantly decreased with long er durations of occlusion. This decay in performance was gradual and h ad a ''half-life'' of greater than 15 sec. Absolute performance was co rrelated across tasks. The effect of occlusion on absolute error in th e localization performance was relatively stable within individuals ov er a 3-week period. The biological utility of guidance information per sistence is discussed along with implications for space constancy, ill usions of motion, and problems of disorientation.