The time course of working memory effects on visual attention

Previous work has generated inconsistent results with regard to what extent working memory (WM) content guides visual attention. Some studies found effects of easy to verbalize stimuli, whereas others only found an influence of visual memory content. To resolve this, we compared the time courses of memory-based attentional guidance for different memory types. Participants first memorized a colour, which was either easy or difficult to verbalize. They then looked for an unrelated target in a visual search display and finally completed a memory test. One of the distractors in the search display could have the memorized colour. We varied the time between the to-be-remembered colour and the search display, as well as the ease with which the colours could be verbalized. We found that the influence of easy to verbalize WM content on visual search decreased with increasing time, whereas the influence of visual WM content was sustained. However, visual working memory effects on attention also decreased when the duration of visual encoding was limited by an additional task or when the memory item was presented only briefly. We propose that for working memory effects on visual attention to be sustained, a sufficiently strong visual representation is necessary. © 2010 Psychology Press

The contribution of stimulus-driven and goal-driven mechanisms to feature-based selection in patients with spatial attention deficits.

When people search a display for a target defined by a unique feature, fast saccades are predominantly stimulus-driven whereas slower saccades are primarily goal-driven. Here we use this dissociative pattern to assess whether feature-based selection in patients with lateralized spatial attention deficits is impaired in stimulus-driven processing, goal-driven processing, or both. A group of patients suffering from extinction or neglect after parietal damage, and a group of healthy, age-matched controls, were instructed to make a saccade to a uniquely oriented target line which was presented simultaneously with a differently oriented distractor line. We systematically varied the salience of the target and distractor by changing the orientation of background elements, and used a time-based model to extract stimulus-driven (salience) and goal-driven (target set) components of selection. The results show that the patients exhibited reduced stimulus-driven processing only in the contralesional hemifield, while goal-driven processing was reduced across both hemifields