Hearing Cheats Touch, but Less in Congenitally Blind Than in Sighted Individuals

The principles of cross-modal integration were investigated with an auditory-tactile illusion in sighted and congenitally blind adults. Participants had to judge the number of rapidly presented tactile stimuli, which were presented together with task-irrelevant sounds. When one tactile stimulus was accompanied by more than one tone, participants reported perceiving more than a single touch. This illusion was more pronounced in sighted than congenitally blind participants. Given that the congenitally blind were more precise in judging the number of tactile stimuli in a control condition without tones, the present data are in accordance with a modality-appropriateness account suggesting that interference by a task-irrelevant modality is reduced if processing accuracy of the task-relevant modality is high.