Abstract
Despite the behavioral and clinical importance of saccade inhibition, the cognitive processes underlying it have remained unclear. Using three different measures, we tested whether marking a location as forbidden to saccades ('don't look' location) involves suppression of perceptual and motor processes at that location. We used a delayed match- or nonmatch-to-sample task in which a cued location has to be memorized either to plan a saccade to it or to avoid making a saccade to it, respectively, when after a delay it reappears alongside a second cue.
First, we measured the spatial allocation of attention during the delay through differences in visual discrimination performance and found that while marking a location as a future saccade target resulted in an attentional benefit at that location, marking it as forbidden to saccades led to an attentional cost. Second, saccade trajectories are known to deviate away from irrelevant distractors present close to the fixation-target path. We found that saccades curved away even more when the item being avoided was at the ‘don’t look’ location as compared to any of the task-irrelevant locations thus suggesting greater inhibition of an explicitly forbidden location in oculomotor programming. Third, by randomly mixing catch trials (one in every four trials; only one target appears at response time) within blocks of match and nonmatch trials, we found that saccades to the catch stimuli at the location memorized as ‘don’t look’ were slower than those at task-irrelevant locations.
We believe this 'don't look' inhibition, elicited at locations that are forbidden to saccades, represents a novel example of inhibition in cognitive processes. It is spatially restricted and temporally persistent over long task durations, which is markedly different from ‘inhibition of return’ that can be detected at adjacent locations as well and dissipates automatically over long delays.
Meeting abstract presented at VSS 2013