The distribution of the perceived direction of motion reported by human observers viewing monocular and dichoptic plaids (see Materials and Methods). a, c, Distribution of the perceived direction of motion for monocular plaids (see icons), expressed relative to the true pattern direction, for individual subjects (a) and averaged across subjects (c). b, d, Distribution of the perceived direction of motion for dichoptic plaids for individual subjects (b) and averaged across subjects (d).