Crossmodal exogenous orienting improves the accuracy of temporal order judgments

Although many studies have demonstrated that crossmodal exogenous orienting can lead to a facilitation of reaction times, the issue of whether exogenous spatial orienting also aVects the accuracy of perceptual judgments has proved to be much more controversial. Here, we examined whether or not exogenous spatial attentional orienting would aVect sensitivity in a temporal discrimination task. Participants judged which of the two target letters, presented on either the same or opposite sides, had been presented Wrst. A spatially non-predictive tone was presented 200 ms prior to the onset of the Wrst visual stimulus. In two experiments, we observed improved performance (i.e., a decrease in the just noticeable diVerence) when the target letters were presented on opposite sides and the auditory cue was presented on the side of the Wrst visual stimulus, even when central Wxation was monitored (“Experiment 2”). A shift in the point of subjective simultaneity was also observed in both experiments, indicating ‘prior entry’ for cued as compared to uncued Wrst target trials. No such JND or PSS eVects were observed when the auditory tone was presented after the second visual stimulus (“Experiment 3”), thus conWrming the attentional nature of the eVects observed. These Wndings clearly show that the crossmodal exogenous orienting of spatial attention can aVect the accuracy of temporal judgments.