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  Top-Down Control Over Visual Contrast Sensitivity

de la Rosa, S., Gordon, M., & Schneider, S. (2007). Top-Down Control Over Visual Contrast Sensitivity. Poster presented at 10th Tübinger Wahrnehmungskonferenz (TWK 2007), Tübingen, Germany.

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 Creators:
de la Rosa, S1, Author           
Gordon, M, Author
Schneider, S, Author
Affiliations:
1External Organizations, ou_persistent22              

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 Abstract: The visual system’s ability to adjust its contrast sensitivity to the ambient contrast level is known as gain control. Previous research has shown that the adjustment of contrast sensitivity is driven by stimulus parameters in a bottom-up fashion [1] and further is under attentional control [2]. Here we present evidence that contrast sensitivity is under top-down control. We paired an absolute identification paradigm with a cueing paradigm to measure identification accuracy for four low contrast stimuli that were intermixed with an occasional high contrast stimulus. Foreknowledge of the presentation of the high contrast stimulus was manipulated by presenting valid and invalid-cues. In Experiment I we found that identification and discriminability of low contrast stimuli was impaired only when the occurrence of the high contrast stimulus was unpredictable but not when it was predictable. Only a top-down gain control mechanism whose functions were to maximize discriminability while protecting the system from overload was consistent with the results. Experiment II provided further support for the idea that an important function of gain control is to protect visual mechanisms from overload. A fit of the Naka-Rushton contrast response model to our data suggested that the top-down control mechanism reduced the effective contrast of the visual pattern (contrast gain) and rescaled the response of contrast sensitive units (response gain).

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 Dates: 2007-07
 Publication Status: Published in print
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Title: 10th Tübinger Wahrnehmungskonferenz (TWK 2007)
Place of Event: Tübingen, Germany
Start-/End Date: 2007-07-27 - 2007-07-29

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Title: 10th Tübinger Perception Conference: TWK 2007
Source Genre: Proceedings
 Creator(s):
Bülthoff, HH1, Editor           
Chatziastros, A1, Editor           
Mallot, HA1, Editor           
Ulrich, R, Editor
Affiliations:
1 Department Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497797            
Publ. Info: Kirchentellinsfurt, Germany : Knirsch
Pages: - Volume / Issue: - Sequence Number: - Start / End Page: 47 Identifier: ISBN: 3-927091-77-4