Abstract
What you've seen before helps you see it again. This effect has been shown in visual search studies looking at the consequence of the previous trial: reaction times are shorter when the features defining a target and distractors are repeated. In this study, I explored whether this bias in attentional selection occurs automatically or whether it depends upon the current goals of observers. Participants performed a visual search task, in which a color and a shape singleton appeared in the search array. The observers were instructed which singleton was relevant at the beginning of every trial.
A previous trial analysis revealed that observers responded sooner when the task, the color of the target, or the shape of the target remained the same across trials. This pattern replicates the outcomes of previous investigations. Importantly, though, these benefits were contingent upon the current task the observers performed: Repeating the color of the previous target facilitated performance only when observers performed the color task and repeating the shape of the previous target facilitated performance only when observers performed the shape task. This pattern did not depend upon the task the observers performed on the previous trial: Everything was ‘remembered’, even though only task relevant repetitions benefited performance. This basic effect became exaggerated when re-analyzing the data on the basis of the previous singletons. Neither color nor shape singletons affected performance when they were irrelevant to the current task. However, when the singleton was relevant to the current task, it facilitated performance when it was the previous target and inhibited performance when it was the previous salient distractor. A two-tired system is required to explain these results: the salient features from the previous trial are remembered, but affect performance only when they are consistent with the observers current goals.
I thank Jolanda Roelofsen for her help with data collection. Funding for this study was provided by the Canadian Institutes of Heath Research and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek.