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Dirk Kerzel, David Souto; Feature-based attention gates motion signals for smooth pursuit. Journal of Vision 2013;13(9):389. doi: 10.1167/13.9.389.
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Attention is necessary for target selection during the initiation and maintenance of smooth pursuit eye movements. We asked whether background motion signals would affect smooth pursuit when they were selected by feature-based attention. Observers pursued a target moving horizontally across a background made up of 40 green and 40 red dots. About 300 ms after target motion onset, the dots moved vertically for 100 ms. One half of the dots moved upwards, while the other half moved downwards. Dots moving in the same direction had the same color. Observers’ primary task was to pursue the horizontally moving target. In addition, they were instructed to attend to one half of the dots and to indicate a small change in their direction of motion. Target and distractor dots were randomly placed such that discrimination could not be based on spatial selection. A vertical ocular tracking response occurred in response to the attended dot motion. The amplitude of the attention-based tracking response was 30% of the tracking response elicited in a single task with only one direction of background motion. Across experiments, we varied the predictability of the vertical direction of the to-be-attended dot motion and found that unpredictable dot motion abolished vertical ocular tracking and reduced discrimination performance. Because of the brevity of the motion signal, it may be too difficult to direct feature-based attention to randomly varying directions of motion. We have established that feature-based attention can gate the motion signals that drive smooth pursuit, even when those are irrelevant to the pursuit task. It appears that unlike the effects of spatial attention, the effects of feature-based attention depend on the repeated presentation of the same relevant features.
Meeting abstract presented at VSS 2013
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