December 2002
Volume 2, Issue 10
Free
OSA Fall Vision Meeting Abstract  |   December 2002
Speed-dependent delays for smooth eye movements
Author Affiliations
  • Jeffrey B. Mulligan
    NASA Ames Research Center, Moffett Field, CA, USA
  • Scott B. Stevenson
    University of Houston College of Optometry, Houston, TX, USA
Journal of Vision December 2002, Vol.2, 20. doi:10.1167/2.10.20
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      Jeffrey B. Mulligan, Scott B. Stevenson; Speed-dependent delays for smooth eye movements. Journal of Vision 2002;2(10):20. doi: 10.1167/2.10.20.

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Abstract

Pursuit eye movements are often modeled by a closed-loop feedback system which attempts to cancel the retinal motion of a target by appropriate control of the eye. Such models predict response delays which depend mainly on the feedback gain and the system loop delay, but do not depend strongly on the amplitude of the input signal itself. We have measured pursuit latencies for tracking of a randomly moving target by cross-correlating the smooth component of eye velocity with the target velocity, obtaining correlograms with a strong peak at around 100 milliseconds. A curious feature of the data is that the delay is increased by 20–40 milliseconds simply by reducing the amplitude of the target trajectory. Similar effects are observed when the contrast of the target is reduced, which we conjecture is the result of a contrast dependent delay in the encoding of the stimulus (albeit relatively late, as there is no contrast version of the Pulfrich effect). A possible explanation for the speed-dependent delay is that spatio-temporal contrast sensitivity reduces the effective contrast of the slowly moving target, making this another variant of the target contrast effect.

Mulligan, J. B. (1998). Pursuit latency for chromatic targets. Investigative Ophthalmology and Visual Science, 39(4), S444.

Mulligan, J. B. (1998). Pursuit latency for chromatic targets. Investigative Ophthalmology and Visual Science, 39(4), S444.

Mulligan, J. B., Stevenson, S. B.(2002). Speed-dependent delays for smooth eye movements [Abstract]. Journal of Vision, 2( 10): 20, 20a, http://journalofvision.org/2/10/20/, doi:10.1167/2.10.20. [CrossRef]
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