Visuo-motor development which causes detection of visual depth from motion and density cues
Keiichiro Tsuji, Keikichi Hayashibe, Masatoshi Hara, Tetsuro Matsuzawa
Examined the effectiveness of cues of visual depth and distance in the course of development and how this process depends on visuo-motor development. In the visual pitfall situation 8 Japanese monkeys (macaca fuscata) were observed with respect to their depth avoidance and visuo-motor activity. The tests were run once a week from the 1st until the 16th wk after birth. Binocular parallax, motion parallax and texture density rates were manipulated to examine their effectiveness as cues. It was shown that for the 1st 2 mo depth perception depended exclusively on motion parallax, whereas in the 3rd mo cues of motion and texture were added. Three items of behavior, head movement, and body movement, were checked and measured to obtain information which could explain the process of development of the cue function. During the 1st month, visual regard closely concurred with head and body movements, then visual activity suppressed motor behavior and, after the end of the 2nd mo, the 2 became almost independent of each other. The authors suggest that these analyses demonstrated that at a later stage pictorial cues produced an effect additional to the primary motion cues and that the effective cue function was based on the development of visuo-motor activity.