Abstracts

To examine the effects of smooth pursuit eye movements on the initiation of saccades, their latency '.vas measured when subjects initially fixated or pursued a target. In half of the block of trials, the fixation or pursuit target was extinguished 200 ms before the saccade target was illuminated (gap trials). Reduction of the mean saccade latency in the gap trials (the ' gap effect') was evident even when the subjects were pursuing a moving target, consistent with previous observations (Krauzlis and Miles 1996). The effect of pursuit direction on saccade latency was also examined. Saccades in the same direction as the preceding pursuit (forward saccades) had shorter latencies than those in the opposite direction (backward saccades). This asymmetry was observed in both the gap and non-gap trials. Although the forward-backward asymmetry was much smaller than the ' gap effect', it was statistically significant in six of eight cases. These results suggest that the preparation of saccades is affected by smooth pursuit eye movements.