The Elephant in the Road: Auditory Perceptual Load Affects Driver Perception and Awareness

Summary. Perceptual load theory research has shown that the level of perceptual load in a task affects processing of additional information. Less certain are the cross-modal effects of perceptual load—does load in one modality affect processing in another? The current study assessed the effect of auditory perceptual load on visual attention in a driving simulator task. While driving, participants listened to traffic updates on the radio, which imposed either low or high perceptual load. Awareness for an unexpected animal as well as less novel objects (such as billboards and other vehicles) was markedly reduced under high load. Driver behaviour was also significantly affected, with impaired lateral control, longer reaction times to hazards and more collisions under high load. This study has important implications for load theory and also more general implications for road safety, as it suggests that auditory load may be an important, often overlooked factor in driver attention.