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Vibrotactile perception are frequency specific. All three experiments found systematic
enhancing effects of sound on somatosensory perception.
Experiment 1
Experiment 1 examined whether an auditory tone affects somatosensory
perception. Thus, a centrally perceived behaviorally-irrelevant sound was
simultaneously presented with a near threshold electrical cutaneous stimulus on the
critical trials. In the baseline trials, the somatosensory stimulus was delivered without
any sound. The detection rates for detecting the somatosensory stimulus with sounds
Wascomparedtothedetectionratesfordetectingitalone.
Methods
After informed consent, twenty participants (10 males; 10 females; mean age =
19.05 years) completed this experiment in exchange for course credit. All subjects were
neurologically normal and reported no hearing or somatosensory deficits.
The somatosensory stimulus, which was generated using an optically isolated
Grass SD9 stimulator, was a 0.3 ms square-wave electrical current that was passed
through a pair of ring electrodes that was attached to the middle finger of the left hand.
The participants comfortably rested their left hand on the armrest of a chair below the
left speaker. In each subject, the intensity of this electrical cutaneous stimulus, which
felt like a faint tap or pulse in the finger, was adjusted to a near-threshold level of 50%
detection by varying intensities across blocks of trials until between 4 and 6 stimuli out