Visual perceptual load modulates an auditory microreflex

The postauricular reflex (PAR) is a vestigial microreflex evoked by an abrupt auditory onset. Previous studies have indicated that the PAR is unaffected by auditory selective attention. Here, we report that the PAR can be modulated by a crossmodal manipulation of attentional demands within the visual modality. Subjects (N=17) performed a central rapid serial visual presentation (RSVP) task while presented with irrelevant auditory distractor probes that elicited the PAR. Visual attentional demands were manipulated by altering the perceptual load of the RSVP task. The PAR modulated systematically with perceptual load, decreasing in amplitude with increased perceptual load. Results indicate that the PAR can be influenced by attention, at least within the visual modality.