Stimulus determinants of brightness and distinctness of subjective contours

Abstract

Subjective contours are characterized by both the appearance of an illusory border and an increase in apparent brightness within the illusory border. Theories have typically addressed only one of these perceptual attributes. The present experiments measured both apparent brightness and apparent border sharpness of stimuli that varied parametrically in number and width of inducing elements and stimulus configuration. It was found that apparent brightness is influenced more by number of inducing elements, whereas apparent sharpness increases more with inducing element width. Stimulus configuration may influence brightness and sharpness differentially. Thus, to be complete, theoretical accounts of subjective contours must address both perceptual attributes. © 1983 Psychonomic Society, Inc.