Post-attentive vision

A large body of research has examined the "preattentive" visual representation of objects; vision prior to the arrival of attention. An even larger body of research concerns attended visual stimuli. Indeed, most vision research involves asking subject to direct attention to some stimulus and to report on it. Very little research has considered post-attentive vision. What is the visual representation of an object after attention has been deployed to that object and, then, deployed elsewhere. Do the effects of attention persist after attention has been removed? Based on a series of eight experiments, we argue that the perceptual effects of attention to an object last only so long as attention is directed to that object. In the experiments reported here, observers are asked to perform the same task repeatedly with the same, unchanging visual stimuli. Experiments One through Six are visual search experiments. In a standard search task, subjects look for a target item in a search display filled with distractors. On each trial, a new search display is presented. In our "repeated search" tasks. The search display is not changed. Subjects search the same display for a new target. The basic finding is that the efficiency of search (as measured by the slope of RT x set size functions) does not change markedly. If a search is inefficient when a display is examined for the first time, it is inefficient when that display is examined the second time, the fifth time or the 300th time. Experiment Seven and Eight make a similar point with a different, curve tracing paradigm. We discuss the implications of this finding for our understanding of scene perception, change detection, and the relationship of vision to memory.