Critical role of foreground stimuli in perceiving visually induced self-motion (vection)

The effects of a foreground stimulus on vection (illusory perception of sel f-motion induced by a moving background stimulus) were examined in two expe riments. The experiments reveal that the presentation of a foreground patte rn with a moving background stimulus may affect vection. The foreground sti mulus facilitated vection strength when it remained stationary or moved slo wly in the opposite direction to that of the background stimulus. On the ot her hand, there was a strong inhibition of vection when the foreground stim ulus moved slowly with, or quickly against, the background. These results s uggest that foreground stimuli, as well as background stimuli, play an impo rtant role in perceiving self-motion.