Abstract
Visual attention plays an important role in encoding objects into VWM (Schmidt et al., 2002). According to one view, VWM and visual attention may reflect the same mechanism (Theeuwes et al., 2009), in which case covertly attending an object should be equivalent to encoding that object into VWM. Alternatively, saccade execution, rather than covert attention, may be the central factor controlling VWM encoding. VWM spans gaps in perceptual input, and a perceptual gap is generated only when a saccade is executed. Thus, VWM consolidation may be tied most directly to pre-saccadic shifts of attention. In the present study, we tested the roles of overt and covert orienting in the automatic encoding of items into VWM. Attention was manipulated during the retention interval of a color change-detection task. Participants either overtly (Experiments 1 and 2) or covertly (Experiments 3 and 4) attended to a task-irrelevant distractor. Distractor encoding was measured by its interference with color memory. The results of Experiments 1 and 2 showed a significant decrease in color memory performance when participants executed a saccade to the distractor object but not when they executed a saccade to empty space. In Experiments 3 and 4, participants covertly shifted attention to the distractor in order to detect a rare onset or discriminate a target presented at the distractor location. Covert shifts of attention did not generate a significant decrease in color memory performance. Participants could strategically avoid encoding a covertly attended object into VWM. Together, the results indicate that encoding of an attended object is automatic only when the shift of attention to that object precedes a saccade. These results challenge the view that visual attention and VWM reflect the same mechanism while supporting the view that perceptual gaps created by saccades necessitate automatic encoding of the saccade-target item into VWM.
Meeting abstract presented at VSS 2012