How automatic are audiovisual links in exogenous spatial attention?

Three experiments on healthy humans investigated the degree of automaticity of crossmodal spatial attention shifts by assessing the intentionality criterion. We used the orthogonal cuing paradigm in which a lateralized cue, either visual or auditory was followed by a unimodal or crossmodal target that occurred at the same or opposite side. In all experiments, the cue was always uninformative as to target location. In Experiment 1, where both side and modality of targets were unpredictable, we found faster discriminations for visual targets following uninformative auditory cues on the same side. This result was replicated in Experiment 2, where target side was blocked and participants could orient attention in advance toward the appropriate side, and in Experiment 3, where they were additionally informed about target modality. Our results suggest that this sort of crossmodal orienting is automatic because it occurred even when participants were provided with detailed information about the target to prevent uninformative auditory cues from orienting attention. This is consistent with the notion that peripheral auditory stimuli are very powerful in capturing visual attention.