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Abstract:
Abstract: The present study explored whether there is a time
course at which audio- visual spatial interactions, or the
'ventriloquist' effect, take place. Subjects judged the elevation
(up vs down, regardless of laterality) of peripheral auditory
targets, following uninformative auditory, visual, or audio-visual
cues. The auditory cues were tones of 100 ms duration on either
side with an intermediate elevation; visual cues consisted of Light
Emitting Diodes (LEDs) positioned at the same location as the
auditory cues; and audio-visual cues consisted of the tone
synchronized with the LEDs at the same location. Saccades were
prevented by monitoring subjects. Judgements were faster for
targets when preceded by an auditory cue on the same side, but
there was no effect of the visual cue, and there was no difference
between the cueing effect of the auditory and audio-visual cues.
LEDs did thus not affect elevation responses to auditory targets.
However, in Experiment 2, peripheral LEDs were synchronized with a
tone that was emitted from a central hidden loudspeaker. This
presumably created a 'ventriloquist' illusion in which the apparent
location of the sound was moved toward the LED. At a Stimulus Onset
Asynchrony (SOA) of 100 ms, the ventriloquist cue did not affect
elevation responses to auditory targets and was similar to a visual
cues, but at SOAs of 300 or 500 ms there were substantial cueing
effects of the ventriloquist cue. These results thus suggest that
the ventriloquist effect has a time course which takes place
between 100 and 300 ms.
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