[The effects of the shape of stripes and the length of target area on White's effect and inverted White's effect].
Two experiments were designed to differentiate White's effect and an inverted White's effect. In White's effect, a gray target bordered by black stripes longer than white stripes appears darker than a target of the same physical luminance bordered by white stripes longer than black stripes when the luminance of the target area lies between the minimum and maximum luminance values of the inducing stripes. In an inverted White's effect, the direction of the effect is reversed when the target is either lighter or darker than both inducing stripes (Spehar, Clifford, & Agostini, 2002). Twenty undergraduates were asked to rate the brightness of a target area using a Munsell scale on the display. The results showed that both White's effect and an inverted White's effect were reproduced in any condition of Experiment 1 and 2. Experiment 1 showed that an inverted White's effect was affected by the shape of stripes, while White's effect was not Experiment 2 showed that an inverted White's effect was affected by the length of target area, while White's effect was not. The results support Spehar et al. (2002) that White's effect and an inverted White's effect are not mediated by the same mechanism.
Umetsu
Sachiko
S
Kumamoto University, Japan. strawberryhappydays@hotmail.com
Watanabe
Isao
I
D005260:Female; D006801:Humans; D007088:Illusions; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*