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Abstract:
Participants were presented with pairs of stimuli, one either
side of fixation, and were required to make unspeeded (left vs.
right) temporal order judgments (TOJs) about which stimulus was
perceived first. Four equiprobable stimulus combinations were used
in the first experiment (VV - visual stimuli on left and right; VT
- visual on left and tactile on right; TT, and TV) and participants
were instructed to divide their attention equally between vision
and touch. On crossmodal trials, the onset of the visual stimulus
had to occur approximately 50 ms before that of the tactile
stimulus in order for the two to be perceived as simultaneous. In
Experiment 2 all VV trials were replaced by TT trials (i.e., 50%
TT, 25% VT, and 25% TV trials) and participants were instructed to
attend to touch. Visual stimuli now had to be occur more than 100
ms before the tactile stimuli for perceptual simultaneity to be
achieved. In Experiment 3 (50% VV, 25% VT, and 25% TV trials)
participants were instructed to attend-vision, and perceptual
simultaneity now coincided with objective simultaneity. By
contrast, performance for intramodal VV and TT pairs was unaffected
by our attentional manipulations. These results suggest that
attending to a modality does not improve temporal resolution within
that modality per se, but instead simply speeds up the processing
of all stimuli in the modality relative to stimulus processing in
other modalities.
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