The name is absent

97

separately for each hand to a near-threshold level at which 4 to 6 stimuli out of ten
were felt. The behaviorally-irrelevant auditory stimulus, which was a pure 500 Hz sine-
wave tone of 200 ms duration, was delivered to either the left or the right ear via Direct
Sound EX-29 Extreme sound-isolating headphones. Because headphones were used,
the intensity of the sound (80 dB) was louder than Experiment 1.

This experiment used a 3 auditory stimulus (none, left, right) x 3 somatosensory
stimulus (none, left, right) factorial design for a total of 9 conditions. Participants
fixated a centrally located light emitting diode (LED), which flashed for 200 ms to signal
the start of each trial. Three hundred ms after fixation offset, one of the nine conditions
was randomly presented with the constraint that no more than two trials in a row were
identical. The participants performed a three-alternative force choice (3-AFC) task,
reporting to the experimenter (who entered the response into the computer) whether a
left somatosensory stimulus, a right somatosensory stimulus, or no somatosensory
stimulus was felt by saying "left," "right," or "none". The next trial began 500 ms after
response input.

AtotalofsGotrialswerecompletedbyeachsubjectinthisexperiment.
Collapsed over left and right stimulation sides, this yielded 80 trials for each of the three
conditions of main interest: somatosensory stimulus without auditory stimulus,
somatosensory stimulus with auditory stimulus on the same side, and somatosensory
stimulus with auditory stimulus on the opposite side of space. The remaining trial types
(the 120 no somatosensory stimulus trials) were included for signal detection analyses.

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