103
Sound on the opposite side from the cutaneous event did not produce a
decrease or cost in its discrimination. Our previous work on vision and touch (Ingeholm,
et al. 2006), using a similar design and paradigm, revealed a large decrement in
performance when a somatosensory stimulus was delivered to the opposite side from
vision. This difference may be explained by the poorer spatial localization capabilities of
the auditory as compared to the visual system, or the fact that the sounds were not
emitted from the precise location of the electrical cutaneous stimuli (i.e. the middle
finger of the hands).
Since auditory coding is more dependent on frequency-based information rather
than precise spatial localization, the enhancing effects on somatosensory processing
from audition may be more readily measured in the frequency-domain. Experiment 3
examined the effects of different frequencies of auditory information on somatosensory
processing.
Experiments
This experiment used different frequencies of auditory and somatosensory
stimuli to assess whether the direct effects of sounds on touch perception are
frequency-dependent. We hypothesized that the effects of sound on Vibrotactile
perception might be restricted to specific frequencies. Indeed, a recent study suggested
that delayed auditory feedback at the same frequency as a Vibrotactile stimuli improved
tactile discrimination performance via acoustic imagery (Iguchi, et al. 2007). To test our
hypothesis, we used either congruent or incongruent frequencies of sound and touch in