Abstract
Working memory representations play a key role in controlling attention, making it possible to shift attention to task-relevant objects. Visual working memory has a capacity of 3-4 objects, but recent studies suggest that only one representation can guide attention at a given moment. To test this, we recorded eye movements during a visual search task in which observers searched for a Landolt-C target in an array of 24 (Experiment 1; half red, half blue) or 32 (Experiment 2; equal numbers of red, yellow, green, and blue) items. Experiment 1 was designed to identify behavioral signatures of template use and template switching. There were three cue conditions in which a color cue at the beginning of the trial validly specified the target color on 100% of trials (100/0 condition), 80% (80/20 condition) or 50% (50/50 condition). The 80/20 condition encouraged observers to begin searching cued-color items, but then switch to searching the uncued-color items if the target had not been located, whereas the non-predictive, 50/50 condition encouraged observers to search randomly across both colors. When observers implemented a single color template in the 80/20 condition, they sequentially searched many consecutive items of a color (long run lengths), and they exhibited a delay prior to switching gaze from one color to another (switch cost). Experiment 2 probed the ability to employ two templates simultaneously. Observers were cued to search two out of the four colors present, and they were instructed to search the two colors either sequentially or simultaneously. In the sequential condition, observers again exhibited long run lengths and a switch cost. In contrast, when searching two colors simultaneously, observers exhibited short run lengths and no switch costs, consistent with the simultaneous guidance of attention by the two cued colors. Thus, multiple working memory representations can guide attention concurrently.
Meeting abstract presented at VSS 2012