Catch the moment: multisensory enhancement of rapid visual events by sound.

Repetition blindness (RB) is a visual deficit, wherein observers fail to perceive the second occurrence of a repeated item in a rapid serial visual presentation stream. Chen and Yeh (Psychon Bull Rev 15:404-408, 2008) recently observed a reduction of the RB effect when the repeated items were accompanied by two sounds. The current study further manipulated the pitch of the two sounds (same versus different) in order to examine whether this cross-modal facilitation effect is caused by the multisensory enhancement of the visual event by sound, or multisensory Gestalt (perceptual grouping) of a new representation formed by combining the visual and auditory inputs. The results showed robust facilitatory effects of sound on RB regardless of the pitch of the sounds (Experiment 1), despite an effort to further increase the difference in pitch (Experiment 2). Experiment 3 revealed a close link between participants' awareness of pitch and the effect of pitch on the RB effect. We conclude that the facilitatory effect of sound on RB results from multisensory enhancement of the perception of visual events by auditory signals.