抄録
Perceptual segmentations with illusory stratification were studied by using silhouettes with competitive perceptual segmentations. One of the conditions for perceptual segmentations and boundary conditions for competitive segmentations in stratification was made clear. For part of a figure to be segmented as a frontal part, the figure must contain edges facing each other or connecting smoothly to each other. The relative length of the illusory contours, perceived in competitive segmentations, determined which segment was perceived as the frontal part. The apparent length of the illusory contour was affected by the existence of parallel illusory contours and by the orientation of the parallel lines constituting a stimulation pattern. The perception of the competitive perceptual segmentations was balanced when the length of the parallel illusory contours was 4/5 of the length of the illusory contours perpendicular to each other.
