Abstract
Purpose: Research on the rubber hand illusion has ever emphasized the role of visual information in locating a tactile sensation on the rubber hand. However, auditory information also serves to locate the tactile sensation along with visual information. Even without visual information, the tactile sensation is produced by a tactile stimulus presented together with auditory stimulus (Hotting and Roder, 2004). We investigated the effect of auditory stimulus on the rubber hand illusion and tactile intensity.
Method: Participants were shown a mirrored image of a left rubber hand but not allowed to see their own left hand directly. Tactile stimuli were given to the participant's own hand and the rubber hand with bars ever 2000 ms under three complex sound conditions (SS (Simultaneous Sound) condition, DS (Delayed Sound) condition, NS (No Sound) condtion). The participants were asked to evaluate perceived ownership of the rubber hand and perceived intensity of the tactile sensation in their own hand.
Result: Perceived ownership of the rubber hand differed with each sound condition. In SS condition, the participants perceived significantly higher ownership of the rubber hand than in DS or NS condition (SS > DS; p < .01, SS > NS; p < .05). Perceived intensity of tactile sensations also differed with each complex sound condition. In SS condition the participants perceived significantly higher intensity of tactile sensations (SS > DS; p < .01, SS > NS; p < .01). These results imply that only when presented simultaneously with a tactile stimulus, the auditory stimulus enhances the perceived ownership of the rubber hand and the tactile intensity, and hence also influences the rubber hand illusion.
This work was supported by Rikkyo University Special Fund for Research.