Abstract
It is well known that prior to a saccade, attention shifts to the saccade goal, improving perceptual discrimination at that location. Here we investigated subjects’ ability to shift attention during a saccade countermanding task, in which they were asked to stop the execution of a saccade for a portion of trials. We hypothesized that stopping the saccade may disrupt the attentional shift to the saccade goal location. Ten subjects discriminated a letter at one of 6 target locations and at the same time performed saccades as fast as possible to one these locations as indicated by a central arrow. A discrimination letter flashed during the saccade latency either at the arrow location 50% of the time (congruent condition) or randomly at one of the other 5 target locations (incongruent condition). During Stop trials (25% of trials), the central arrow turned red, indicating to subjects not to make a saccade; the central arrow turned red at different delays (0-150ms) after it appeared (stop signal delay - SSD). The longer the SSD, the less able subjects were at stopping the saccade. For successful Stop trials, discrimination performance was significantly better in the congruent condition (60%) compared to the incongruent condition (39.8%). However, for the congruent condition, performance was much lower than that of successful Go trials (78.6%). Performance was also significantly lower than performance in the congruent condition in a covert attention control without eye movements (80.2%). In summary, while there still remains a certain amount of attention at the saccade goal when the saccade is stopped, it is greatly reduced compared to when it is not stopped or when a saccade is never required. These results suggest that stopping a saccade affects the attention shift to that location and that attention is disrupted by saccade inhibition processes.
Meeting abstract presented at VSS 2012