The detection of real and apparent concomitant rotation in a three-dimensional cube: Implications for perceptual interactions

Apparent concomitant rotation, such as that seen when viewers move laterally relative to a depth-reversed three-dimensional wire cube, has been taken as evidence that perceived distance must precede perceived motion, a proposal that is consistent with taking-into-account theories. Another proposal has been that apparent concomitant motion arises from attention to proximal motion and, hence, cannot support general claims about motion perception. In two experiments, moving viewers saw 700-msec exposures of a cube biased to be seen in either veridical or reversed depth. The cube either rotated or remained stationary. Viewers rated the perceived rotation, using a 4-point scale. The results suggested that depth cues interact with other variables before perceived rotation is computed. Surprisingly, rotations that included a substantial apparent concomitant motion component were rated higher than equivalent rotations that included no illusory motion. This asymmetry suggests that taking-into-account theories must be amended.