Intensity dependent interaction in audiovisual integration

Ventriloquism is one of the most exciting phenomena in multimodal perception. It refers to a percept when an auditory and a visual stimulus coincide but has different spatial origin, and the latter attracts the location of the sound on the perceptual level. A huge number of studies revealed how and when certain properties of the constituting modalities interact during the processing of multimodal information. However none of them dealt with one of the most prominent aspect of real world signals, namely their intensity. We used high and low intensity audio and visual signals in a task where participants were asked to decide whether the sound came from left or right. Results showed that only high intensity visual stimuli attracted sound locations. We found also that response times for high intensity sounds increased in conditions where they were presented with high intensity visual stimuli on the opposite side. These results suggest that spatial ventriloquism depends on stimulus intensity.