Sound enhances touch perception.

Certain sounds, such as fingernails screeching down a chalkboard, have a strong association with somatosensory percepts. In order to assess the influences of audition on somatosensory perception, three experiments measured how task-irrelevant auditory stimuli alter detection rates for near-threshold somatosensory stimuli. In Experiment 1, we showed that a simultaneous auditory stimulus increases sensitivity, but not response biases, to the detection of an electrical cutaneous stimulus delivered to the hand. Experiment 2 demonstrated that this enhancement of somatosensory perception is spatially specific--only monaural sounds on the same side increased detection. Experiment 3 revealed that the effects of audition on touch are also frequency dependent--only sounds with the same frequency as the vibrotactile frequency enhanced tactile detection. These results indicate that auditory information influences touch perception in highly systematic ways and suggest that similar coding mechanisms may underlie the processing of information from these different sensory modalities.