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Katherine Burnett, Isabel Arend, Avishai Henik; The automaticity and timecourse of motion processing. Journal of Vision 2015;15(12):277. doi: https://doi.org/10.1167/15.12.277.
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© ARVO (1962-2015); The Authors (2016-present)
Because of its biological relevance, motion processing may be prioritized, or processed automatically. We tested this by combining shape and motion dimensions in the same task. An arrow pointing to the left or right contained a flowfield of left- or right-moving dots, and participants responded to either arrow direction or motion direction. A congruity effect was present for both tasks, indicating that arrow direction and motion direction are processed automatically. There was a significant Task X Congruity interaction, as the arrow direction produced a larger congruity effect on the motion task than the motion direction produced on the arrow task. Reaction time (RT) was faster for the arrow than the motion task, suggesting that the interaction may be due to the processing time associated with each task. We therefore analysed the RT distributions using a binning procedure. For the arrow task, a congruity effect was absent at short RTs. For the motion task, a congruity effect was seen across RTs. We proposed that arrow direction interfered more - and earlier - with the motion task because it was resolved more quickly. In order to test this proposal, we manipulated the stimuli. Firstly, we removed the arrow border to increase arrow direction RTs. Secondly, we increased the speed of motion to decrease motion direction RTs. Both manipulations altered the overall task RTs as predicted, but did not modify the timecourse of interference on the arrow task. A final experiment mixed the tasks into one pre-cued block, in which the Task X Congruity interaction was significant and the timecourse asymmetries remained. In conclusion, we present some evidence that motion processing is automatic. However, interference effects from motion processing are consistently seen later in the timecourse of a shape processing task, despite efforts to encourage similar processing speeds for the two dimensions.
Meeting abstract presented at VSS 2015
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