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Matthew Hilchey, John Christie, Jay Pratt; Dissociating inhibitory mechanisms with actions and objects. Journal of Vision 2016;16(12):1277. doi: 10.1167/16.12.1277.
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© 2017 Association for Research in Vision and Ophthalmology.
Our hypothesis is that that the inhibition found a few hundred milliseconds following the presentation of a peripheral cue can be dissociated into two completely separate mechanisms. One mechanism biases action against the direction of previously programmed saccades (action-based inhibition) whereas the other biases perception against covertly processed visual inputs (attention-based inhibition). This study manipulates hand position (action) and placeholder presence (objects) to demonstrate this dissociation. In Experiment 1, we mapped the time course of covert peripheral cueing with and without placeholder objects while instantiating strict eye movement controls and requiring manual responses to visual stimuli. Crucially, inhibition was obtained only when placeholder objects were present. In a second experiment, where participants made eye movements to the cues and then returned to fixation, we found inhibition when placeholders were present or absent. Experiment 3 further distinguished between these forms of inhibition by manipulating hand position. Across four separate blocks, we manipulated whether the participants' hands were near or far from the visual display and whether they made an eye movement or not to the cue. With eye movements to the cues, inhibition was amplified in near- relative to far- hand space. When gaze was held at fixation, inhibition was attenuated in near- relative to far- hand space. Collectively, the findings suggest that action-based inhibition is amplified by hand proximity and is encoded in space-based coordinates whereas attention-based inhibition is attenuated by hand proximity and is encoded principally in object-based coordinates.
Meeting abstract presented at VSS 2016
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