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Publication Detail
The Neural Correlates of Crowding-Induced Changes in Appearance
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Anderson EJ, Dakin, S.C. , Schwarzkopf, D.S. , Rees, G. , Greenwood, J.
  • Publication date:
    2012
  • Journal:
    Current Biology
  • Volume:
    In press
Abstract
Object recognition in the peripheral visual field is limited by crowding: the disruptive influence of nearby clutter [1, 2]. Despite its severity, little is known about the cortical locus of crowding. Here, we examined the neural correlates of crowding by combining event-related fMRI adaptation with a change-detection paradigm [3]. Crowding can change the appearance of objects, such that items become perceptually matched to surrounding objects; we used this change in appearance as a signature of crowding and measured brain activity that correlated with the crowded percept. Observers adapted to a peripheral patch of noise surrounded by four Gabor flankers. When crowded, the noise appears oriented and perceptually indistinguishable from the flankers. Consequently, substituting the noise for a Gabor identical to the flankers ('change-same') is rarely detected, whereas substituting for an orthogonal Gabor ('change-different') is rarely missed. We predicted that brain areas representing the crowded percept would show repetition-suppression on 'change-same' trials, but release from adaptation on 'change-different' trials. This predicted pattern was observed throughout V1-V4, increasing in strength from early to late visual areas. These results depict crowding as a multi-stage process, involving even the earliest cortical visual areas, with perceptual consequences that are increasingly influenced by later visual areas.
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Inst Ophthalmology - Visual Neuroscience
Inst Ophthalmology - Visual Neuroscience
Experimental Psychology
Imaging Neuroscience
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