November 2002
Volume 2, Issue 7
Vision Sciences Society Annual Meeting Abstract  |   November 2002
Latency of smooth pursuit under conditions of stimulus-response uncertainty
Author Affiliations
  • Marian E. Berryhill
    Dartmouth College
Journal of Vision November 2002, Vol.2, 179. doi:
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      Marian E. Berryhill, Leanne Boucher, Kestutis Kveraga, Howard C. Hughes; Latency of smooth pursuit under conditions of stimulus-response uncertainty. Journal of Vision 2002;2(7):179.

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      © ARVO (1962-2015); The Authors (2016-present)

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Hick's law predicts that response latencies increase as a log2 function of the number of stimulus-response (S-R) alternatives. However, earlier findings by our group demonstrate that visually guided saccades (prosaccades) violate Hick's law. Prosaccadic response latencies do not increase as the number of S-R alternatives rises logarithmically from 1 to 8. In the present study, we investigated the applicability of Hick's law to smooth pursuit eye movements (SPEM). Subjects were asked to pursue a moving dot which moved from the center of the screen outwards 6 degrees. We varied S-R uncertainty by varying the number of possible movement trajectories the dot could move within a block of trials to either 1, 2, 4, or 8 possible directions. The level of S-R uncertainty was made salient before each trial by presenting 1, 2, 4 or 8 arrows indicating the potential movement trajectories for that particular trial. We found that the latency to initiate smooth pursuit does not depend on the number of S-R alternatives and thus violates Hick's law. Our finding suggests that probabilistic knowledge of target movement direction is not employed by the smooth pursuit system to reduce SPEM latency.

Berryhill, M. E., Boucher, L., Kveraga, K., Hughes, H. C.(2002). Latency of smooth pursuit under conditions of stimulus-response uncertainty [Abstract]. Journal of Vision, 2( 7): 179, 179a,, doi:10.1167/2.7.179. [CrossRef]

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