Perception of Depth in Rotating Objects: 6. Effects of Fixation and Pursuit on the Phenomenal Motion of Stereokinesis

Abstract

Stereokinetic percepts, including fluctuations in the anchor point mechanism, occurred regardless of whether O fixated points before, at, or behind the center or to the side of the stimulus. Fixation of a point on the periphery of a coarsely textured circle rotating slowly in the frontal plane yielded percepts of the textural dots slowing down before they passed the fixation point and speeding up afterward. Pursuit at moderate speeds of one circle of a circle-pair as a cylinder was being perceived resulted in disruption of the cylinder without destroying the apparent depth. The non-pursued circle became blurred “pure” movement, but upon switching the pursuit to this circle, these positive afterimages instantly disappeared and reappeared in the other face.