Abstract
Inhibitory mechanisms have long been hypothesized to operate in parallel with facilitatory mechanisms in selection of information. However, visual selection has predominantly been studied in the context of signal enhancement at specific locations. We investigated whether active and task-dependent (as opposed to reflexive) inhibition of specific locations can be used as a complementary strategy in visuo-spatial tasks. 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. We found that while marking a location as a future saccade target, expectedly, resulted in a spatial selection benefit at that location, marking it as forbidden to saccades led to a cost in spatial selection specific to that location. We further show that, first, the spatiotemporal dynamics of these amplificatory and inhibitory effects were characteristically different from each other. Second, this spatial cost could be sustained over long task delays, which to our knowledge, is the first demonstration of the capacity to sustain spatially selective inhibition. Third, detection of pop-out visual search targets at the inhibited location was found to be impaired, showing that the observed inhibitory effects were mediated by biased selection at early stages of visual information processing. Our results suggest that like selective attention, selective spatial inhibition is an active visual mechanism that can be called into play to subserve visual and response selection requirements.
Meeting abstract presented at VSS 2014