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Anna Klapetek, Donatas Jonikaitis; Tracking choices before they are made: Saccadic decisions bias perceptual selection . Journal of Vision 2016;16(12):1049. doi: https://doi.org/10.1167/16.12.1049.
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© ARVO (1962-2015); The Authors (2016-present)
There is ample evidence that saccadic decisions are represented in the oculomotor system, but our understanding of the underlying mechanisms is limited, as we can normally only observe the consequences of the decisions in the form of eye movements. In the present study we investigated whether decision making can be traced before a particular response is selected and executed, and measured this in free choice and rule-based choice situations. For this purpose we took advantage of the fact that the oculomotor system facilitates perceptual selection at the goals of planned saccades. Participants were asked to memorize two spatial locations, highlighted by different colors. After a delay period, the color of the central fixation changed and either indicated one of the memorized locations as the saccade target (rule-based choice), or indicated to freely choose between the two locations. By probing discrimination performance at variable SOAs relative to this cue, we were able to measure the time course of the perceptual selection of both targets. In both rule-based and free choice trials, we observed a parallel perceptual selection of the chosen saccade target and the non-chosen target. Despite the fact that both targets were selected, there was a clear bias towards the saccade target. This bias was evident before correct as well as before erroneous rule-based responses. In conclusion, our results demonstrate that motor decisions have direct sensory consequences. This offers a new way of how decision making in the human oculomotor system can be traced.
Meeting abstract presented at VSS 2016
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