Visual memory as measured by classification and comparison tasks.

One measure often used to indicate the existence of visual memory is visual priming, that is, faster responding to a stimulus physically identical to its predecessor than to one identical in name only. Walker and Marshall (1982) used visual priming within speeded classification tasks to demonstrate a visual memory effect that does not seem to require active visualization to prevent decay or to prevent being over-written by succeeding stimuli. This article presents six experiments with classification tasks that not only replicate Walker and Marshall's finding of a strong visual memory in the absence of visualization but also--contrary to their results--show visual priming even after an unpredictable intervening visual pattern. Four additional experiments with comparison tasks show visual priming effects only when stimulus-response contingencies remain consistent. Although this result seems to favor an explanation of the visual priming effect based on stimulus-response contingencies, it does not totally rule out explanations based on stimulus-identification processes, assuming that inconsistent stimulus-response contingencies interfere with the benefits that stimulus repetition may have on stimulus identification.