Saccades curve away from previously inhibited locations: evidence for the role of priming in oculomotor competition

Abstract

The oculomotor system serves as the basis for representing concurrently competing motor programs. Here, we examine whether the oculomotor system also keeps track of the outcome of competition between target and distractor on the previous trial. Participants had to perform a simple task of making a saccade toward a predefined direction. On two-thirds of the trials, an irrelevant distractor was presented to either the left or right of the fixation. On one-third of the trials, no distractor was present. The results show that on trials without a distractor, saccades curved away from the empty location that was occupied by a distractor on the previous trial. This result was replicated and extended to cases when different saccade directions were used. In addition, we show that repetition of distractor location on the distractor-present trials results in a stronger curvature away and in a shorter saccade latency to the target. Taken together, these results provide strong evidence that the oculomotor system automatically codes and retains locations that had been ignored in the past to bias future behavior.