Primacy of spatial information in guiding target selection for pursuit and saccades.

Previous studies have examined the facilitative effects of prior spatial information on target selection for saccadic eye movements. More recently, studies have shown that prior spatial information also influences target selection for smooth pursuit. However, direct comparisons of the effects of prior information on target selection for pursuit and saccades have not been made. To this end, we provided different classes of prior information and measured their effects on target selection for pursuit and saccades. In Experiment 1, we assessed the relative effects of spatial cues (indicating the target stimulus' initial location) and color cues (indicating the target stimulus' color) on eye movement latencies. In Experiment 2, we assessed the effects of motion cues (indicating the target stimulus' direction of motion) in addition to spatial cues. For both pursuit and saccades, we found that spatial cues reduced eye movement latencies more than color cues (Experiment 1). Spatial cues also reduced eye movement latencies more than motion cues (Experiment 2), even for pursuit, despite the fact that stimulus motion is essential for the generation of pursuit eye movements. These results indicate that both pursuit and saccades are affected to a greater degree by spatial information than motion or color information. We suggest that the primacy of spatial information for both pursuit and saccades reflects the importance of spatial attention in selecting the stimulus target for both eye movements.