Suppressive and facilitatory spatial interactions in peripheral vision: peripheral crowding is neither size invariant nor simple contrast masking.

Full Abstract

Peripheral vision is characterized by reduced spatial resolution and inhibitory spatial interactions that extend over long distances. This work had three goals. (1) We considered whether the extensive crowding in peripheral vision is a consequence of a shift in the spatial scale of analysis. To test this, using a large range of target sizes and spatial frequencies, we measured the extent of crowding for targets that were limited in their spatial frequency content. (2) We considered whether crowding in peripheral vision can be explained on the basis of contrast masking by remote flanks. To test this hypothesis, we measured and compared crowding in a direction-identification experiment with masking by remote flanks in a detection experiment. In each of the experiments, our targets and flanks were composed of Gabor features, thus allowing us to control the feature contrast, spatial frequency, and orientation. (3) We examined the relationship between the suppressive and facilitatory interactions in peripheral contrast detection and crowding. Our results show that unlike the normal fovea (Levi, Klein, & Hariharan, 2002), peripheral crowding is not scale invariant nor is it attributable to simple contrast masking. Rather, our results suggest that inhibitory spatial interactions in peripheral crowding extend over larger distances than in the fovea for targets of the same size. In peripheral vision, the critical distance for crowding is approximately 0.1 times the target eccentricity. Observers can easily detect the features that compose our targets (Gabor patches) under conditions where crowding is strong. Thus, we speculate that peripheral crowding occurs because the target and flanks are combined or pooled at a second stage, following the stage of feature extraction. In peripheral vision, this pooling takes place over a large distance.

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Author information

Author/s: Levi, Dennis M (DM); Hariharan, Srividhya (S); Klein, Stanley A (SA);

Affiliation: School of Optometry, University of California, Berkeley, CA, USA. dlevi@spectacle.berkeley.edu

Grants: P30EY07551 (Agency:United States NEI) ; R01 EY04776 (Agency:United States NEI) ; R01EY01728 (Agency:United States NEI) ; T35EY0708 (Agency:United States NEI)

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, P.H.S.

Journal: Journal of vision (J Vis), published in United States. (Language: eng)

Reference: 2002-; vol 2 (issue 2) : pp 167-77

Dates: Created 2003/04/07; Completed 2003/04/16; Revised 2008/04/29;

PMID: 12678590, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Contrast Sensitivity - physiology
Humans
Perceptual Masking - physiology

Perceptual Masking - physiology
Space Perception - physiology
Vision - physiology

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