August 2010
Volume 10, Issue 7
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2010
Covert attention affects second-order contrast sensitivity
Author Affiliations
  • Antoine Barbot
    Department of Psychology, New York University
  • Michael S. Landy
    Department of Psychology, New York University
    Center for Neural Science, New York University
  • Marisa Carrasco
    Department of Psychology, New York University
    Center for Neural Science, New York University
Journal of Vision August 2010, Vol.10, 262. doi:10.1167/10.7.262
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      Antoine Barbot, Michael S. Landy, Marisa Carrasco; Covert attention affects second-order contrast sensitivity. Journal of Vision 2010;10(7):262. doi: 10.1167/10.7.262.

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

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Abstract

Covert spatial attention affects contrast sensitivity for first-order, luminance-defined patterns, increasing sensitivity at the attended location, while reducing sensitivity at unattended locations relative to a neutral-attention condition. Humans are also sensitive to “second-order” patterns, e.g., spatial variations of texture. Second-order sensitivity is typically modeled using a cascade of a linear filter tuned to one of the constituent textures, a nonlinearity (rectification) yielding stronger positive responses to regions containing that texture, and a second spatial filter to enhance texture modulations. Here, we assessed whether covert attention affects sensitivity to second-order, texture-defined contrast. Methods: Stimuli were orientation-defined, second-order, sine-wave gratings. A vertical or horizontal grating was used to modulate between two carrier textures (gratings with higher spatial frequency, oriented at ±45°). Second-order modulator and first-order carrier phases were randomized. Observers judged the orientation (vertical or horizontal) of the modulator. Orientation-discrimination performance was measured as a function of modulator contrast. Stimuli appeared in four isoeccentric locations (5° eccentricity). Exogenous (involuntary) attention was manipulated with a brief peripheral precue adjacent to one of the stimulus locations. Target location was indicated by a response cue after stimulus presentation, yielding three cue conditions: valid (precue matched response cue), invalid (mismatched) and neutral (all stimulus locations precued). Results: Covert attention increased second-order contrast sensitivity at the attended location, while decreasing it at unattended locations, relative to the neutral condition. These effects were more pronounced at high second-order contrasts. The magnitude of improvement was a function of second-order modulator spatial frequency and independent of first-order carrier spatial frequency, and thus could not be explained by increased sensitivity to the carriers. The results indicate that attention improves second-order contrast sensitivity.

Barbot, A. Landy, M. S. Carrasco, M. (2010). Covert attention affects second-order contrast sensitivity [Abstract]. Journal of Vision, 10(7):262, 262a, http://www.journalofvision.org/content/10/7/262, doi:10.1167/10.7.262. [CrossRef]
Footnotes
 Support: NIH R01-EY016200 to MC and R01-EY16165 to MSL.
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