U-shaped backward contour masking during stroboscopic motion.

Two stationary and spatially separated visual stimuli, presented briefly and successively in time, are known to produce stroboscopic motion whose vividness is a U-shaped function of the stimulus onset asynchrony. Contour masking is also known to occur under such stimulus conditions. The findings show that the contour masking is confined to only the first stimulus and that it, like metacontrast, is a backward U-shaped function of the stimulus onset asynchrony. A simple model, based on known psychophysical and neurophysiological properties, is proposed to explain these results.