FORWARD-FACING MOTION BIASES FOR RIGID AND NONRIGID BIOLOGICALLY LIKELY TRANSFORMATIONS

When observers are presented directionally ambiguous motion, they exhi bit a bias for experiencing movement in the direction in which shapes appear to face. We examined the influence of rigidity of a shape on th e forward-facing bias with stimuli whose directionality is biologicall y specified. In general, the lack of shape correspondence during a non rigid transformation should weaken the motion percept and decrease for ward-facing bias. In contrast, representational momentum cues associat ed with a biologically likely nonrigid transformation should enhance t he motion percept and increase forward-facing bias. Analysis for both rigid and nonrigid conditions indicated statistically significant forw ard-facing biases, bur strength of bias did not differ significantly. The lack of difference between the two conditions suggests that the tr ansformation was not one which allowed the influence of either consist ency of correspondence or representational momentum to dominate and co nfirms that a comparably sized forward-facing bias can occur with both rigidly and nonrigidly transformed shapes.