THE WHITE EFFECT AND KANIZSA MODAL AMODAL COMPLETION

When gray and black alternating bars in white and black alternating gr ids were observed through a stereoscope, the visual system detects an imaginary rectangle of gray bars which appeared in the rear or front s tereoscopic plane. The rectangle in the rear stereoscopic plane looked amodally completed and opaque dark gray. The dark gray was caused by the contrast with the white background. The rectangle in the front ste reoscopic plane looked modally completed, translucent and blackish. Th e black was caused by the assimilation to the black grids in the rear stereoscopic plane. When the rectangle was moved to and fro horizontal ly, both rear and front rectangles looked more vivid and blacker. Thes e results indicate that both contrast and assimilation are closely rel ated to object perception in the real world, reminiscent of Kanizsa's modal and amodal completions. When a focal area is admitted as a thing , two phenomena tend to occur; one is called contrast, which exaggerat es the difference between the thing and the not-thing, while the other is called assimilation, which neglects any differences within the thi ng.