Abstract
Walking is arguably the most frequent movement in bipeds (e.g., humans) and quadrupeds, and is often accompanied with footsteps. Here we report an investigation into the effects of auditory cues on invisible biological motion processing. A standard high contrast dynamic noise pattern was presented to one eye, and a test motion sequence (i.e., a point-light walker) was gradually introduced to the other eye so that it was rendered invisible through interocular suppression at the beginning of each trial. We measured the time for the stimulus to break from noise suppression and begin to gain dominance. Meanwhile, auditory beeps either congruent or incongruent with the pace of the point-light walker were presented. Results showed that point-light walkers paired with congruent auditory beeps emerged from suppression into awareness faster than those paired with incongruent beeps. The modulation effect, however, was strongly impaired when the biological motion stimuli were shown upside down. Our findings suggest that auditory cues can be automatically integrated with biological motion processing even in the absence of conscious awareness.
This research was supported by the Knowledge Innovation Program of Chinese Academy of Sciences (KSCX2-YW-R-248 and 09CX202020) and National Natural Science Foundation of China.