Contour integration and perceptual fading
36.519, Sunday, May 12, 2:45 - 6:45 pm, Vista Ballroom
Lars Strother1,2, Danila Alferov1, Tutis Vilis1,2; 1Brain and Mind Institute, University of Western Ontario, 2Department of Physiology and Pharmacology, University of Western Ontario
The association field (Field et al. 1993) model of contour integration predicts that contours comprised of sufficiently proximal edge elements become increasingly detectable with decreasing inter-element misalignment. We investigated a possible relationship between the association field and the perceptual fading of a contour under conditions of impending camouflage. We measured the effect of inter-element alignment on the duration of continued contour visibility using contours that were visible upon onset but faded into a camouflaging background within a few seconds. Even though the elements comprising the contours remained superimposed on the background, the contours always became fully camouflaged within a few seconds after contour onset. Our method allowed us to study the effects of inter-element orientation for considerably greater inter-element distances than those used in detection experiments. We used a continuous range of angular deviations from collinearity. This resulted in a parametric effect of inter-element alignment on the duration of perceptual fading such that contours comprised of maximally co-aligned elements remained visible (~500 ms) longer than those comprised of more randomly oriented elements. Consistent with findings from contour detection studies, contours remained visible longest (> 3 s) when co-aligned elements were parallel to the global contour (snakes) as compared to perpendicular (ladders). We conclude that the effect of inter-element alignment on delayed contour fading reflects the sustained operation of an association field mechanism. This mechanism binds discrete visual elements into global contours as a function of synchronous onset, inter-element distance and element co-alignment.