Publications

Abstract

Detection of change when one display of familiar objects replaces another display might be based purely upon visual codes, or also on identity information (i.e., knowing what was present where in the initial display). Displays of 10 alphanumeric characters were presented and, after a brief offset, were presented again in the same position, with or without a change in a single character. Subjects' accuracy in change detection did not suggest preservation of any more information than is usually available in whole report except with the briefest of offsets (under 50 msec). Stimulus duration had only modest effects. The interaction of masking with offset duration followed the pattern previously observed with unfamiliar visual stimuli (Phillips, 1974). Accuracy was not reduced by reflection of the characters about a horizontal axis, suggesting that categorical information contributed negligibly. Detection of change appears to depend upon capacity-limited visual memory; (putative) knowledge of what identities are present in different display locations does not seem to contribute.