Individual differences in working memory capacity and visual search: the roles of top-down and bottom-up processing.

Individual differences in working memory capacity (WMC) have been implicated in a variety of top-down, attention-control tasks: Higher WMC subjects better ignore irrelevant distractions and withhold habitual responses than do lower WMC subjects. Kane, Poole, Tuholski, and Engle (2006) recently attempted to extend these findings to visual search, but found no relation between WMC and search efficiency, even in difficult tasks yielding steep search slopes. Here we used a visual search task that isolated the contributions of top-down versus bottom-up mechanisms, and induced a habitual response via expectation. Searches that relied primarily on bottom-up mechanisms did not vary with WMC, but searches that relied primarily on top-down mechanisms showed an advantage for higher over lower WMC subjects.