August 2012
Volume 12, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2012
Parallel extraction of information for foveal analysis and peripheral selection of where to look next
Author Affiliations
  • Casimir Ludwig
    School of Experimental Psychology, University of Bristol, Bristol Vision Institute
  • Rhys Davies
    School of Experimental Psychology, University of Bristol, Bristol Vision Institute
  • Miguel Eckstein
    Department of Psychological and Brain Sciences, University of California Santa Barbara,
Journal of Vision August 2012, Vol.12, 1246. doi:10.1167/12.9.1246
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      Casimir Ludwig, Rhys Davies, Miguel Eckstein; Parallel extraction of information for foveal analysis and peripheral selection of where to look next. Journal of Vision 2012;12(9):1246. doi: 10.1167/12.9.1246.

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

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Abstract

In natural vision the cycle of fixations and gaze shifts demands analysis of visual information at the currently fixated region for object recognition and identification, but also of the periphery to select the target for the next gaze shift. We asked how time during a fixation is allocated to the foveal discrimination and peripheral selection tasks, and how this allocation depends on the difficulty of foveal discrimination. Observers performed a visual comparison task in a limited period of time. A Gabor patch at fixation fluctuated in contrast and orientation. The mean orientation was offset from vertical in either the clockwise or anti-clockwise direction. Three peripheral patterns also fluctuated in contrast and orientation. One of the peripheral patterns had a higher mean contrast. Observers judged whether the target orientation was the same or different from the patch at initial fixation. The difficulty of the orientation discrimination forced observers to generate a saccade to the target in order to accomplish the comparative judgement. The foveal discrimination and peripheral selection tasks were defined by different visual dimensions. We analysed the noise in both dimensions to identify the temporal epochs during which the information for both tasks was extracted. Orientation information at the fovea was extracted throughout the entire fixation period, right up to saccade initiation. The integration epoch for peripheral selection was shorter and overlapped with the foveal discrimination window. Variation in the difficulty of foveal discrimination did not affect the duration of the integration window. Foveal discrimination and peripheral selection occur in parallel during fixation, with relatively little time spent on analysing peripheral information for saccade target selection. Fixation duration and the duration of the integration window are not under online direct control by the currently experienced processing difficulty.

Meeting abstract presented at VSS 2012

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