Experimental Brain Research

, Volume 159, Issue 2, pp 268–272 | Cite as

Effect of stimulus probability on anti-saccade error rates

  • Michael J. Koval
  • Kristen A. Ford
  • Stefan Everling
Research Note


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.


Eye 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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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Michael J. Koval
    • 1
  • Kristen A. Ford
    • 3
    • 4
  • Stefan Everling
    • 1
    • 2
    • 3
    • 4
  1. 1.Department of Physiology and PharmacologyUniversity of Western OntarioLondonCanada
  2. 2.The Centre for Brain and MindRobarts Research InstituteLondonCanada
  3. 3.Department of PsychologyUniversity of Western OntarioLondonCanada
  4. 4.Graduate Program in NeuroscienceUniversity of Western OntarioLondonCanada

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