Effect of stimulus probability on anti-saccade error rates
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Subjects sometimes fail to suppress a reflexive saccade towards the flashed stimulus in an anti-saccade task. Here, we studied how error rates in the anti-saccade task varied as a function of saccadic probability. Ten subjects performed 200 anti-saccade trials for each of three saccade-direction probability conditions (20%, 50%, and 80%). We found that as the likelihood of a saccade in a given direction increased, the percentage of pro-saccade errors also increased for stimulus presentations in this direction. These results provide support for the hypothesis that errors in the anti-saccade task are the result of an increased level of motor preparation.
KeywordsEye movements Motor preparation Antisaccade Inhibition
We thank Matthew Brown for his assistance in data analysis. We also thank two anonymous reviewers for very helpful comments on the manuscript. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the National Alliance for Research on Schizophrenia and Depression (NARSAD). S.E. is a Canadian Institutes of Health Research New Investigator and an EJLB Research Scholar.
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