Perception of verticality by monkeys

When visual and postural cues of verticality were put into conflict, responses of monkeys oscillated in long runs between the available cues. When visual cues were not relevant to perceiving the vertical, Ss readily employed postural cues. Tilt from the vertical proved to be more discriminable than extraneous cues, and 1 rhesus monkey was able to discriminate a vertical cylinder from 1 tilting less than 1°. Although human Ss were able to make finer discriminations than monkeys, the distributions of DLs for 2 groups nearly overlapped. (PsycINFO Database Record (c) 2006 APA, all rights reserved).