The curvature of saccade trajectories is modulated by advanced knowledge of target location but is not spatially sensitive to distractor location

Abstract

It has been shown that the trajectories of saccadic eye movements curve away from distractors in some situations, while in other situations (such as visual search) saccades curve towards distractors. We examined the hypothesis that saccades made to predictable targets will curve away from distractors (due to the presence of top-down inhibition) while saccades made to unpredictable targets will be more likely to curve towards a distractor. It was found that the direction of curvature (towards or away from distractors) changed depending on prior knowledge of target location. Saccades curved towards distractors when target location was unpredictable and curved away from distractors when the target location was pre-cued. In further experiments the spatial extent of the presumed inhibitory process involved in producing curvature away from distractors was examined by systematically manipulating the target to distractor separation. Although there was an effect of side (saccades curved away from distractors) and hemifield (greatest curvature when distractor in target hemifield) there was no clear relationship between curvature and target to distractor separation. The findings are discussed in terms of competitive interactions operating in the saccadic system.

Leverhulme Trust Grant