Abstract

Traditionally, contour interaction has been investigated at the visual acuity limit using a Landolt C and flanking bars, performance being quantified in terms of a percent correct measure. More recently, it has been shown that the properties of the contour interaction are different when larger stimuli are used: Contour interaction is not polarity specific, and spatial frequency tuning for an unflanked C is broader. Here we quantify contour interaction for stimuli 5× larger than the resolution limit in terms of contrast thresholds. We show that polarity of bars has little effect on unfiltered stimuli but does show very different effects on the spatial-frequency-tuning curves for discrimination of the Landolt C. This explains the polarity dependence of crowding at the visual acuity limit and its independence for larger unfiltered targets. Thus the underlying filtering function is composed of more than one mechanism, affected differently depending on the relative polarity of the test and flank contours.

© 2003 Optical Society of America

Foveal contour interaction: detection and discrimination

Oliver Ehrt and Robert F. Hess
J. Opt. Soc. Am. A 22(2) 209-216 (2005)

Contour interaction for an easily resolvable stimulus

Robert F. Hess, Cristyn B. Williams, and Asif Chaudhry
J. Opt. Soc. Am. A 18(10) 2414-2418 (2001)

Contour interaction in fovea and periphery

Robert F. Hess, Steven C. Dakin, Neil Kapoor, and Marc Tewfik
J. Opt. Soc. Am. A 17(9) 1516-1524 (2000)

Visual Resolution and Contour Interaction*

Merton C. Flom, Frank W. Weymouth, and Daniel Kahneman
J. Opt. Soc. Am. 53(9) 1026-1032 (1963)

Hierarchy of spatial interactions in the processing of contrast-defined contours

Peter Wenderoth, Colin W. G. Clifford, and Anna Ma Wyatt
J. Opt. Soc. Am. A 18(9) 2190-2196 (2001)