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Casimir J. H. Ludwig, Iain D. Gilchrist, Eugene McSorley; Spatial frequency dependencies of the remote distractor effect in saccade programming. Journal of Vision 2004;4(8):638. doi: 10.1167/4.8.638.
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When a distractor appears in close temporal proximity to a target, the target-directed saccade is delayed. We explored how this remote distractor effect (RDE) depends on the spatial frequency of the target and distractor. In three experiments, a target gabor patch appeared at 4 or 8 degrees eccentricity on the horizontal midline. Saccade direction was blocked so that the target always appeared in the left or right visual field. On the majority of trials a contralateral distractor appeared simultaneously with the target. The observer's task was to saccade to the target patch. We systematically varied the spatial frequency content of the target and distractor. We obtained a robust RDE with low to medium spatial frequency distractors (1 – 4 c/deg), regardless of the spatial frequency of the target (2, 4, or 8 c/deg). A similar distractor effect was obtained with high spatial frequency distractors (8 c/deg), but only when the target was of the same spatial frequency. This latter finding was not caused by the additional time available for distractor processing that resulted from the overall increase of the latencies for the 8 c/deg target. We suggest that the RDE is mediated by the distractor activity in channels that respond to low - medium spatial frequencies. Overlap in the channels activated by the target and distractor only becomes an important factor when the target spatial frequency is high. This study integrates basic oculomotor research with fundamental vision science in order to characterise the spatial frequency sensitivity of the saccadic system.
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