The Effect of Brightness Contrast on the Apparent Length of the Diagonal of a Parallelogram
恵治 浜口 · Institutional Repositories DataBase (IRDB) · 1988
Ａparallelogram has two diagonals (long and short ones).The long one is called a long diagonal, and the short one a short diagonal here.This paper is concerned with the effect of brightness contrast between figure and ground on the apparent lengths of the long diagonal (the first experiment) and the short diagonal (the second experiment).Parallelograms and diagonals were varied independently in brightness contrast.In the firstexperiment the apparent lengths of long diagonals were underestimated.The differences in brightness between parallelogram and diagonal reduced the illusion, and ａ maximal illusion was found when the parallelogram and the diagonal had the same brightness.In the second experiment the apparent lengths of short diagonals were overestimated, but brightness differencesbetween parallelogram and diagonal gave no noticeable change in the sizeof the illusion｡