The oculomotor salience of flicker, apparent motion and continuous motion in saccade trajectories

The aim of the present study was to investigate the impact of dynamic distractors on the time-course of oculomotor selection using saccade trajectory deviations. Participants were instructed to make a speeded eye movement (pro-saccade) to a target presented above or below the fixation point while an irrelevant distractor was presented. Four types of distractors were varied within participants: (1) static, (2) flicker, (3) rotating apparent motion and (4) continuous motion. The eccentricity of the distractor was varied between participants. The results showed that saccadic trajectories curved towards distractors presented near the vertical midline; no reliable deviation was found for distractors presented further away from the vertical midline. Differences between the flickering and rotating distractor were found when distractor eccentricity was small and these specific effects developed over time such that there was a clear differentiation between saccadic deviation based on apparent motion for long-latency saccades, but not short-latency saccades. The present results suggest that the influence on performance of apparent motion stimuli is relatively delayed and acts in a more sustained manner compared to the influence of salient static, flickering and continuous moving stimuli.