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ExperimentZ
Experiment 2 examined whether the effects of sound on somatosensory
perception are Iateralized. Instead of a central sound and a left-hand somatosensory
stimulus, as in Experiment 1, the auditory and somatosensory stimuli were delivered to
either the left or right of the subject. Thus, the auditory and somatosensory stimuli
could be on the same or opposite sides when the sound was presented. Furthermore,
Experiment 2 used a set of sound-isolating headphones rather than speakers to
Iateralize the sounds and to eliminate any potential effects or interactions on
somatosensory processing from air pressure. We hypothesized that, compared with the
no auditory stimulus condition, a congruent auditory stimulus on the same side as the
somatosensory stimulus would improve somatosensory discrimination while an
incongruent sound on the opposite side would result in poorer discrimination.
Methods
After informed consent, twenty participants (8 males; 12 females; mean age =
19.15 years) who did not participate in Experiment 1 completed this experiment in
exchange for course credit. All subjects were neurologically normal and reported no
hearing or somatosensory deficits.
As in Experiment 1, the somatosensory stimuli were near-threshold electrical
stimuli that were delivered through ring electrodes attached to the middle finger of the
left and right hands. Each subject comfortably positioned their left and right hands on
the arms of their chair. The somatosensory stimulation intensity was first adjusted