donderdag 18 augustus 2011

The same binding in contour integration and crowding

http://www.journalofvision.org/content/11/8/10.short

 

The same binding in contour integration and crowding

1.  Ramakrishna Chakravarthi Author Home PageSend Mail to Author1,2 and

2.  Denis G. Pelli Author Home PageSend Mail to Author3

+Author Affiliations

1.       1Université de Toulouse, CerCo, UPS, France
2.       2CNRS, UMR 5549, Faculté de Médecine de Rangueil, Toulouse, France
3.       3Department of Psychology and Center for Neural Science, New York University, New York, NY, USA

Abstract

Binding of features helps object recognition in contour integration but hinders it in crowding. In contour integration, aligned adjacent objects group together to form a path. In crowding, flanking objects make the target unidentifiable. However, to date, the two tasks have only been studied separately. K. A. May and R. F. Hess (2007) suggested that the same binding mediates both tasks. To test this idea, we ask observers to perform two different tasks with the same stimulus. We present oriented grating patches that form a “snake letter” in the periphery. Observers report either the identity of the whole letter (contour integration task) or the phase of one of the grating patches (crowding task). We manipulate the strength of binding between gratings by varying the alignment between them, i.e., the Gestalt goodness of continuation, measured as “wiggle.” We find that better alignment strengthens binding, which improves contour integration and worsens crowding. Observers show equal sensitivity to alignment in these two very different tasks, suggesting that the same binding mechanism underlies both phenomena. It has been claimed that grouping among flankers reduces their crowding of the target. Instead, we find that these published cases of weak crowding are due to weak binding resulting from target–flanker misalignment. We conclude that crowding is mediated solely by the grouping of flankers with the target and is independent of grouping among flankers.

 

 

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Lee de-Wit (PhD), Post-Doctoral Researcher

Gestalt ReVision Project, University of Leuven.

https://sites.google.com/site/leehdewit/

http://ppw.kuleuven.be/labexppsy/gestaltrevision/

lee.dewit@psy.kuleuven.be, ++32 16 326 143

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