The relationship between visual attention and visual working memory encoding: A dissociation between covert and overt orienting

Abstract

There is substantial debate over whether visual working memory (VWM) and visual attention constitute a single system for the selection of task-relevant perceptual information or whether they are distinct systems that can be dissociated when their representational demands diverge. In the present study, we focused on the relationship between visual attention and the encoding of objects into VWM. Participants performed a color change-detection task. During the retention interval, a secondary object, irrelevant to the memory task, was presented. Participants were instructed either to execute an overt shift of gaze to this object (Experiments 1-3) or to attend it covertly (Experiments 4 and 5). Our goal was to determine whether these overt and covert shifts of attention disrupted the information held in VWM. We hypothesized that saccades, which typically introduce a memorial demand to bridge perceptual disruption, would lead to automatic encoding of the secondary object. However, purely covert shifts of attention, which introduce no such demand, would not result in automatic memory encoding. The results supported these predictions. Saccades to the secondary object produced substantial interference with VWM performance, but covert shifts of attention to this object produced no interference with VWM performance. These results challenge prevailing theories that consider attention and VWM to reflect a common mechanism. In addition, they indicate that the relationship between attention and VWM is dependent on the memorial demands of the orienting behavior. (PsycINFO Database Record

Figure 1

Sequence of events in a trial of Experiment 1. The top row illustrates a trial in which the secondary object was absent. The middle row illustrates a SO-present trial in the Saccade block. The bottom row illustrates a SO-present trial in the Fixation block. The eye image shows participant’s gaze positon during the events.

Figure 2

Mean proportion correct on the color change-detection task plotted as a function of block type and secondary object presence in Experiment 1. Error bars represent 95% confidence intervals based on the object presence effect in each block.

Figure 3

Schematic illustration of the events in a Saccade and No Saccade trial of Saccade (no target) condition of Experiment 2.

Figure 4

Mean proportion correct on the color change-detection task in Experiment 2. Error bars represent 95% confidence intervals based on the effects of secondary object presence in the Saccade and Fixation blocks, and on the effect of saccade execution in the Saccade (no target) block.

Figure 5

Mean proportion correct on the color change-detection task in Experiment 3 as a function of block type. Error bars are 95% confidence intervals based on the effect of block type.

Figure 6

Sequence of events in a trial of Experiment 4. The top row illustrates an SO-absent trial. The middle row illustrates a trial in which the secondary object was present but no target dot appeared. The bottom row illustrates a SO-present trial on which a target dot appeared. When a target dot appeared, it was presented at the object location on 73.3% of trials (valid) and on the opposite side of the screen on 26.7% of trials (invalid).

Figure 7

Mean proportion correct on the color change-detection task plotted as a function of block type and secondary object presence in Experiment 4. Error bars represent 95% confidence intervals based on the effect of object presence in each block.

Figure 8

Illustration of the retention interval events for trials on which a masked discrimination target (“T” or inverted “T”) was present in Experiment 5. The top row shows a valid trial (73.3% of target-present trials). The bottom row shows and invalid trial (26.7% of target-present trials)

Figure 9

Mean proportion correct on the color change-detection task plotted as a function of block type and secondary object presence in Experiment 5. Error bars represent 95% confidence intervals based on the effect of object presence in each block.