ORIENTATION ANISOTROPY - INCIDENCE AND MAGNITUDE IN CAUCASIAN AND CHINESE SUBJECTS

Cutoff spatial frequencies for sine-wave gratings were measured at 4 orientations for 100 Caucasian and 24 Chinese subjects, all of whom were raised in carpentered environments. For the Caucasian subjects, average acuity for horizontal and vertical gratings was superior to that for obliques by about 1/4 of an octave. About 10% of subjects failed to show the effect. The Chinese subjects showed an anisotropy of about 1/8 of an octave. The carpentered environment explanation of orientation anisotropy cannot, in its present form, account for the wide variety of response patterns obtained, nor the differences between Chinese and Caucasian subjects.