Suppressive and facilitatory spatial interactions in foveal vision: foveal crowding is simple contrast masking.

Full Abstract

Spatial interactions are a critical and ubiquitous feature of spatial vision. These interactions may be inhibitory (reducing sensitivity as occurs in crowding) or facilitatory (enhancing sensitivity). In this work, we had four goals. 1. To test the hypothesis that foveal crowding depends on target size by measuring the extent of crowding for novel targets that were limited in their spatial frequency content. We used a large range of target sizes and spatial frequencies. 2. To assess whether the critical spatial frequency model (Hess, Dakin, & Kapoor, 2000) provides a general model for foveal crowding. To test this model, we measured crowding for a direction-identification task that did not require judging the orientation of the gap. 3. To test the hypothesis that foveal crowding is simply contrast masking by remote flanks 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. 4. To assess the relationship between suppressive and facilitatory spatial interactions in foveal vision. Our results show that (1) foveal crowding is proportional to feature size over the more than 50-fold range of target sizes that we examined. Over this large range, foveal crowding is scale invariant. Our results also show it is the size of the envelope (SD) rather than the carrier (SF) that determines the extent of crowding in the fovea. 2. Crowding that occurs in the direction-identification task is quite similar to crowding where orientation information is available. Thus we conclude that the critical spatial frequency model does not provide a general explanation for foveal crowding. 3. Threshold elevation for crowding is similar to threshold elevation for masking as predicted by our test-pedestal model. Thus we conclude that foveal crowding is simple contrast masking. 4. Based on our comparison of threshold changes in crowding and masking, we conclude that in foveal vision, the suppressive spatial interactions due to nearby flanks are similar in the two tasks. However, the facilitatory interactions are quite different. In the crowding task, we find very little evidence for facilitation by flankers, whereas in the detection task, we find strong facilitation. We suggest that facilitation of detection by remote flanks may be, at least in part, a consequence of uncertainty reduction.

Learn Faster Today Improve your study skills

Author information

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

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

Grants: P30EY07551 (Agency:United States NEI) ; R01EY01728 (Agency:United States NEI) ; R01EY04776 (Agency:United States NEI) ; T35EY07088 (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 140-66

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

PMID: 12678589, 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.

External Links for this article (including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Contrast Sensitivity - physiology
Fovea Centralis - physiology
Humans

Pattern Recognition, Visual - physiology
Perceptual Masking - physiology
Space Perception - physiology

This article has not been indexed for related articles as yet, however you can still use the live related article search links below.

See 100+ related articles.