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

Abstract

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.

Perceptual load affects change blindness in a real‐world interaction

“…In line with our second hypothesis, participants were less likely to notice the change under high perceptual load. Although many studies have shown that high perceptual load increases inattentional blindness (Cartwright‐Finch & Lavie, ; Murphy & Greene, ) and impairs eyewitness memory and ability to pick out an individual from a line‐up (Greene et al, ; Murphy & Greene, ), the current study is just the second to demonstrate increased change blindness under perceptual load, the first using human faces.…”

“…Such a consideration might also extend beyond the visual modality as there is evidence that perceptual load has cross‐modal effects on awareness. For example, auditory perceptual load has been shown to increase inattentional blindness for an unexpected object (Murphy & Greene, ), and visual load has been shown to increase inattentional deafness (Macdonald & Lavie, ; Murphy & Greene, ) and inattentional numbness (Murphy & Dalton, ). Likewise, there is an auditory analogue of change blindness, “change deafness” (Vitevitch, ).…”

“…This can be manipulated by either increasing the amount of material to be processed (Lavie & De Fockert, ;e.g., detect a target letter surrounded by one neutral letter vs. six neutral letters), by increasing the complexity of the material to be processed (Beck & Lavie, ;e.g., detect a target letter surrounded by six target‐dissimilar letters vs. six target‐similar letters), or by presenting the same material, but increasing the complexity of the judgement to be made (Cartwright‐Finch & Lavie, ;e.g., determine which arm of a cross is a particular color vs. determine which arm of a cross is fractionally longer). As perceptual capacity is limited, the load model states that when a task imposes high perceptual load, irrelevant distractors are less likely to be processed, resulting in less behavioral interference by distractors (Lavie, ; Forster & Lavie, ; Lavie & De Fockert, ; Murphy & Greene, ; Murphy & Greene, ). Perceptual load effects are distinct from effects of task difficulty or general clutter in a scene, as high perceptual load results in longer reaction times and increased errors (as does greater task difficulty) but, crucially, reduces interference from distractors (unlike task difficulty; Lavie & De Fockert, ).…”

“…The role of perceptual load on awareness has also been demonstrated across other modalities, with studies demonstrating increased inattentional deafness (Macdonald & Lavie, ) and inattentional numbness (Murphy & Dalton, ) under high perceptual load. Reduced awareness under load has been demonstrated in driving, with increased perceptual load resulting in inattentional blindness for a large roadside elephant (Murphy & Greene, ) and a pedestrian about to cross the road (Murphy & Greene, ), as well as inattentional deafness for driving and non‐driving related sounds (Murphy & Greene, ).…”

Attentional resources contribute to the perceptual learning of talker idiosyncrasies in audiovisual speech

“…Given our results, it seems unlikely that the load imposed by the auditory distractor task could have impacted visual processing, since it is unclear, then, why load would have affected the outcomes of recalibrating only auditory, but not visual, phonetic categories. The few prior studies examining whether auditory perceptual load can affect visual processing have shown mixed results (Berman & Colby, 2002;Houghton, Macken, & Jones, 2003;Murphy & Greene, 2017;Rees, Frith, & Lavie, 2001). Nonetheless, overall the literature suggests that while resources are at least partially shared audiovisually in spatial attention, object-based attention (which we manipulated in our study) taps into modalityspecific pools of attentional resources unless a primary task needs to be prioritized over a secondary task to give a speeded response .…”