Abstract

We examine the mechanism that subserves visual contour detection and particularly its tuning for the spatial frequency of contour components. We measured the detection of contours composed of Gabor micropatterns within a field of randomly oriented distractor elements. Distractors were randomly assigned one of two spatial frequencies, and elements lying along the contour alternated between these values. We report that the degree of tolerable spatial-frequency difference between successive contour elements is inversely proportional to the orientation difference between them. Spatial-frequency tuning (half-width at half-height) for straight contours is $\sim 1.3$ octaves but, for contours with a 30° difference between successive elements, drops to $\sim 0.7$ octaves. Integration of curved contours operates at a narrower bandwidth. Much orientation information in natural images arises from edges, and we propose that this narrowing of tuning is related to the reduction in interscale support that accompanies increasing edge curvature.

© 1998 Optical Society of America

Relationship between facilitation at threshold and suprathreshold contour integration

Cristyn B. Williams and Robert F. Hess
J. Opt. Soc. Am. A 15(8) 2046-2051 (1998)

Spatial frequency tuning of brightness polarity identification

Viljami R. Salmela and Pentti I. Laurinen
J. Opt. Soc. Am. A 22(10) 2239-2245 (2005)

Role of synchrony in contour binding: some transient doubts sustained

Steven C. Dakin and Peter J. Bex
J. Opt. Soc. Am. A 19(4) 678-686 (2002)

Integration of first- and second-order orientation

Harriet A. Allen, Robert F. Hess, Behzad Mansouri, and Steven C. Dakin
J. Opt. Soc. Am. A 20(6) 974-986 (2003)

Foveal contrast thresholds exhibit spatial-frequency- and polarity-specific contour interactions

Oliver Ehrt, Robert F. Hess, Cristyn B. Williams, and Khurram Sher
J. Opt. Soc. Am. A 20(1) 11-17 (2003)