Abstract
Bistable perception occurs during binocular rivalry when one eye views vertically moving dots while the other eye's dots move horizontally. Which eye's view dominates perception switches unpredictably over time. Bistable perception also occurs with ambiguous motion, dots moving along elliptical trajectories as though on the surface of a transparent sphere. In this case, dots on the “near” surface of the sphere appear to switch motion directions unpredictably over time; left or right if the ellipse major axes are horizontal, up or down if the major axes are vertical. Multistable perception occurs when one eye views an ambiguous motion stimulus with ellipse major axes horizontal while the other eye views ambiguous motion with major axes vertical. Dots on the “near” surface of the perceived sphere appear to switch directions unpredictably among left, right, up or down. The model I wished to test was that multistable switching rate could be predicted by combining the bistable switching rate of ambiguous motion viewed without rivalry (i.e., binocularly), and the bistable switching rate of binocular rivalry between similar unambiguous motion stimuli. [The latter were created by using only one half of each elliptical trajectory for the moving dots, giving appearances of opaque rotating spheres.] Multistable switching rate should increase when the rivaling stimuli have their own non-zero switching rate. To my surprise, eye dominance times lengthened when orthogonal axes of ambiguous motion were presented dichoptically (4.09 +/− 1.15, 1975; mean +/− SD, N collapsed across 14 observers) relative to unambiguous motion (2.63 +/− 1.13, 3692). Motion direction dominance times shortened in rivalry (2.92 +/− 1.00, 2974) relative to no rivalry (3.60 +/− 1.00, 2311). Dominance times that began or ended with an eye switch, thus potentially truncated, did not differ from direction dominance times embedded in within-axis runs. Multistable switching rate fell between the bistable rates.
I thank all students who took EXP 4174 Summer 2001 — Spriong 2003.