The name is absent

95

Signal detection analyses were also conducted to assess the changes in
sensitivity independent of or at least with minimal influences from response biases. For
this analysis, d' values for the two auditory stimulus conditions were calculated from the
hit (detection report when a somatosensory stimulus present) and false alarm
(detection report with no somatosensory stimulus) rates and subjected to a two-tailed
paired t-test. There were significantly higher d^, values for detecting the somatosensory
stimulus with the sound present (d' = 2.81) as compared to the sound absent conditions
(d^, = 2.40; t₁₉ = 2.721, p = .014). The c values to measure any potential response biases
were also calculated for each auditory stimulus condition. There were no differences in
response biases between the sound present (c = .99) vs. sound absent (c - .97)
conditions (t₁g = 0.16, p = .88), indicating that the effects of the sound were not a
Consequenceofshiftsinresponsecriteria.

These results indicate that a task-irrelevant sound can enhance somatosensory
perception. The sounds in this experiment were perceived to come from directly in
front of the subject, while the somatosensory stimuli were delivered to only the left
hand. This spatial separation might have limited the increase in somatosensory
perception because previous studies in our laboratory have shown that the enhancing
effects ofvision on somatosensory perception are spatially specific (Johnson, et al.
2006). Therefore, Experiment 2 asked whether spatial congruence is important for the
effects of audition on somatosensation.

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