POLARITY MATCHING IN THE TERNUS CONFIGURATION

Two experiments were conducted to examine the effect of changes in the sign of element contrast on perceptions of the Ternus apparent motion display. In the first experiment, the contrast polarity of all three elements in the display were alternated from the first frame of view t o the second. At short durations, this increased perceptions (relative to a control condition) of simultaneity in the display, decreased per ceptions of element motion, and did not significantly affect perceptio ns of group motion. At long durations, this manipulation did not affec t performance. In a second experiment, patterns of element polarity we re manipulated to favour perceptions of either element motion or of gr oup motion relative to a control condition in which all elements had i dentical contrast polarity. At a long duration, this manipulation affe cted perceptions of the configuration; this manipulation did not affec t the appearance of the display at a short duration. Together, these r esults are inconsistent with the predictions of Grossberg and Rudd's [ Psychological Review, 99, 78-121 (1992)] motion oriented contrast filt er. However, they are consistent with a model of motion correspondence processing that includes a polarity matching constraint.