Abstract

Using a 2-D stochastic display, we have observed a global 3-D percept. Our stimulus is a dynamic random-dot cinematogram in which each dot takes an independent 2-D random walk of constant step size. From one frame to the next, each dot’s direction of displacement is chosen at random from a uniform distribution of directions. When the range of this distribution is <150° the percept appears to be that of a rotating cylindrical volume whose axis of rotation is along the mean of the distribution. When the range of the distribution is >150° there is no 3-D percept. As the directional distribution of the stimulus is slowly changed, the occurrence and loss of the 3-D percept shows hysteresislike behavior. This behavior is not altered by large changes in dot density or display area, suggesting a form of local cooperativity. Our results are discussed in the context of cooperative interactions that may be involved in the recovery of structure from motion.

© 1986 Optical Society of America