Effects of Lightness Contrast and Fundus Pigmentation on Age-Related Decrement in Magnitude of the Mueller-Lyer Illusion

Abstract

Components of the Mueller-Lyer figure, representing two levels of lightness contrast (1.5 black/ and 7.5 light grey/ each on 9.5 white/ ground) were viewed tachistoscopically for 500 msec. by 65 white elementary school children and 50 white college students. The contrast effect was significant, with black figures yielding a greater illusion than the light grey figures at all age levels. Further, a bimodal distribution of fundus density was evident in both age categories, with more densely pigmented Ss yielding smaller illusions.