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Pedro Cardoso-Leite, Andrei Gorea; Comparison of perceptual and motor decisions via confidence judgments and saccade curvature. Journal of Vision 2009;9(8):832. doi: 10.1167/9.8.832.
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© ARVO (1962-2015); The Authors (2016-present)
A major challenge in cognitive sciences is the appraisal of the relationship between perception and action and of the subtending biological processes. Here we address this general issue by investigating the link between the subjective visibility of close to threshold distractors and the trajectory parameters of saccades directed to a highly visible target. This study investigated the effects on perceptual and motor decisions of low-contrast distractors, presented 5° on the left and/or the right of the fixation point. Perceptual decisions were assessed with a Yes/No (distractor) detection task. Motor decisions were assessed via these distractors' effects on the trajectory of an impending saccade to a distinct imperative estimulus, presented 10° above fixation 50 ms after the distractor(s). Results show that saccades curve away from distractors only when observers report them to be present(perceptual Hits and False Alarms). Furthermore, saccade deviation is correlated (on a trial-by-trial basis) with the inferred internal response associated with the perceptual report: the stronger the distractor-evoked perceptual response, the more saccades deviate away from the distractor. Also, in contrast with a supersensitive motor system, perceptual sensitivity is systematically higher than the motor sensitivity derived from the distributions of the saccades' curvatures. When both distractors are present (and straight saccades are expected), the sign of saccades' curvature is correlated with observers' perceptual bias/criterion. Overall the results point to a strong perceptual-motor association and demonstrate that saccade trajectories betray observers perceptual state.
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