The remote distractor effect of saccade latencies in fixation-offset and overlap conditions.

Saccadic responses to a visual target are delayed if another visual stimulus (distractor) is presented in the visual field opposite to the target (remote distractor effect). In the present study, two experiments were conducted to investigate how the remote distractor effect is modulated by the presence or absence of a central fixation stimulus. In both experiments, when a fixation stimulus was continuously presented even after target presentation, the remote distractor effect decreased. The reduction of the remote distractor effect was observed for all distractor positions examined (1.5 degrees -9.0 degrees eccentricity), and prominent especially when targets were presented at more peripheral positions (9.0 degrees and 10 degrees eccentricity). It was concluded that these results can be well explained by recent findings on inhibitory interactions among subpopulations of neurons in the superior colliculus.