Abstract
Prominent theories of attention claim that visual search is guided through attentional templates stored in working memory. Recently, the contralateral delay activity (CDA), an electrophysiological index of working memory storage, has been found to rapidly diminish when observers repeatedly search for the same target, suggesting that, with learning, the template moves out of working memory. However, this has only been investigated for pop-out search for a distinct color target, for which a strong top-down attentional guidance is not necessary. We hypothesized that more effortful search tasks, in which there is no guidance from a distinct color, might rely, to a greater extent, on an active attentional template in working memory. This would predict a slower handoff to long term memory, and thus a slower decline of the CDA. Using ERPs, we compared the rate of learning of attentional templates in pop-out and effortful search tasks. Unexpectedly, the rate of learning an attentional template, as indexed by the rate of decrease in the CDA, was the same for both search tasks. Similar results were found for a second component indexing working memory activity, the late positive complex, or LPC. However, the LPC was also sensitive to anticipated search difficulty, as was expressed in a greater amplitude prior to the harder search task. We conclude that the amount of working memory activity invested in maintaining an attentional template, but not the rate of learning, depends on search difficulty.
Meeting abstract presented at VSS 2014