Viewer-centered temporal biasing of 3-D rotation percepts.

The perceived direction of rotation of a 3-D cloud of dots can be biased by a prior rotation (Jiang, Pantle, and Mark, 1998 Perception & Psychophysics 60 275-286). In a series of experiments, it is shown that the temporal rotation bias is reversed by a 180 degrees change of head orientation between two rotation sequences; i.e. the perceived direction of rotation reverses for the second of two sequences when head orientation is changed. The bias is, therefore, viewer-centered. Perceptual reversals are not obtained when the orientation of the head is changed and returned to its original position between rotation sequences. It was also found that the viewer-centered bias combined additively with viewer-independent near-far luminance information. Finally, the bias was manifest when 3-D depth was re-established, but not maintained, between rotation sequences. A model, in descriptive and flowchart forms, is used to explain the integration of world-centered information and a viewer-centered temporal bias on the presence/absence of perceptual reversals of the rotating virtual sphere. In the model, the temporal bias is the result of the coupling of depth values to persisting 2-D retinal motion signals.