Crossmodal attentional capture in an unspeeded simultaneity judgment task.

We report an experiment designed to examine whether or not crossmodal attentional capture affects the performance of participants in an unspeeded simultaneity judgement (SJ) task. Sixteen participants made completely unspeeded judgements as to whether two visual targets (one presented on either side of fixation) had been presented simultaneously or else successively. A spatially nonpredictive auditory cue was presented on one side 200 ms before the onset of the first visual target. The results showed that the uncued visual target had to be presented 17 ms before the cued visual target in order for the two stimuli to be perceived as simultaneous. This result is consistent with the view that the automatic crossmodal capture of attention that follows the presentation of a spatially nonpredictive peripheral auditory cue leads to the speeding-up of the sensory processing of visual stimuli presented at the cued (relative to the uncued) location.