Lateral inhibition and the location of visual contours: An analysis of figural after-effects

Abstract

Figural after-effects refer to the displacements which one visual contour induces on a neighboring contour, the two figures being presented successively. In this study, we examine under retinally stabilized conditions the effect of one visual contour on the detection and apparent location of a second contour. It is shown that contours are generally displaced towards each other in appearance when their separation is less than 3 min of arc and generally displaced away from each other with somewhat larger separations. At these inter-contour distances, contours exert inhibitory effects on each other's detection. Similar threshold effects have been noted in the presence of Mach Bands, known to be a manifestation of lateral inhibition. It is suggested that the contour displacements may be manifestations of the same edge-effects. The temporal separation of the two contours, presumably the distinguishing attribute of an after-effect, is shown not to be a significant variable.