Volume 5, Number 9, Article 3, Pages 678-689 doi:10.1167/5.9.3 http://journalofvision.org/5/9/3/ ISSN 1534-7362
Shared decision signal explains performance and timing of pursuit and saccadic eye movements
Dorion Liston
Salk Institute for Biological Studies, La Jolla, CA, USA, & Department of Neuroscience, University of California, San Diego, CA, USA
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Richard J. Krauzlis
Salk Institute for Biological Studies, La Jolla, CA, USA
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Abstract

Each voluntary eye movement provides physical evidence of a visuomotor choice about where and when to look. Primates choose visual targets with two types of voluntary eye movements, pursuit and saccades, although the exact mechanism underlying their coordination remains unknown. Are pursuit and saccades guided by the same decision signal? The present study compares pursuit and saccadic choices using techniques borrowed from psychophysics and models of response time. Human observers performed a luminance discrimination task and indicated their choices with eye movements. Because the stimuli moved horizontally and were offset vertically, subjects' tracking responses consisted of combinations of both pursuit and saccadic eye movements. For each of two signal strengths, we constructed speed–accuracy curves for pursuit and saccades. We found that speed–accuracy curves for pursuit and saccades have the same shape, but are time-shifted with respect to one another. We argue that this pattern occurs because pursuit and saccades share a decision signal, but utilize different response thresholds and are subject to different motor processing delays.

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History
Received December 18, 2004; published October 10, 2005
Citation
Liston, D., & Krauzlis, R. J. (2005). Shared decision signal explains performance and timing of pursuit and saccadic eye movements. Journal of Vision, 5(9):3, 678-689, http://journalofvision.org/5/9/3/, doi:10.1167/5.9.3.
Keywords
pursuit, saccades, speed–accuracy tradeoff, choice behavior, response threshold
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