Volume 9, Number 2, Article 12, Pages 1-15 doi:10.1167/9.2.12 http://journalofvision.org/9/2/12/ ISSN 1534-7362
Supercrowding: Weakly masking a target expands the range of crowding
Timothy J. Vickery
Department of Psychology, Yale University, New Haven, CT, USA
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Won Mok Shim
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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Ramakrishna Chakravarthi
Department of Psychology, New York University, New York, NY, USA
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Yuhong V. Jiang
Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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Robert Luedeman
Department of Psychology, Harvard University, Cambridge, MA, USA
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Abstract

Crowding is impairment of peripheral object identification by nearby objects. Critical spacing (the minimum target-flanker distance that does not produce crowding) scales with target eccentricity and is consistently reported as roughly equal to or less than 50% of target eccentricity (0.5e). This study demonstrates that crowding occurs far beyond the typical critical spacing when the target is weakly masked by a surrounding contour or backwards pattern mask. A target was presented at a peripheral location on every trial and participants reported its orientation. Flankers appeared at target-flanker distances of 0.3–0.7e, or were absent. The target was presented with or without a mask. When flankers were absent, the masks only mildly impaired performance. When flankers were present but the mask was absent, target identification was nearly perfect at wide target-flanker distances (0.5e–0.7e). However, when flankers were present and the target was masked, performance dropped significantly, even when target-flanker distances far exceeded the typical crowding range. This phenomenon (“supercrowding”) shares critical features with standard crowding: flankers similar to the target impair performance more than dissimilar flankers, and the characteristic anisotropic profile of crowding is preserved. Supercrowding may reflect a general interaction between crowding and other forms of masking.

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History
Received August 21, 2008; published February 10, 2009
Citation
Vickery, T. J., Shim, W. M., Chakravarthi, R., Jiang, Y. V., & Luedeman, R. (2009). Supercrowding: Weakly masking a target expands the range of crowding. Journal of Vision, 9(2):12, 1-15, http://journalofvision.org/9/2/12/, doi:10.1167/9.2.12.
Keywords
crowding, masking, object recognition, spatial vision
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