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Citation
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Strayer DL, Cooper JM, Turrill J, Coleman J, Medeiros-Ward N, Biondi F. Washington, DC: AAA Foundation for Traffic Safety, 2013 |
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Abstract
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Driver distraction from secondary in-vehicle activities is increasingly recognized as a significant source of injuries and fatalities on the roadway. The National Highway Traffic Safety Administration (NHTSA) has issued driver distraction guidelines to address visual and manual sources of distraction, but there are currently no published standards that explicitly and exclusively apply to cognitive distraction.
The goal of the current research was to establish a systematic framework for measuring and understanding cognitive distraction in the vehicle. In this report, we describe three experiments designed to systematically measure cognitive distraction.
The first experiment served as a control in which participants performed eight different tasks without the concurrent operation of a motor vehicle. In the second experiment, participants performed the same eight tasks while operating a high-fidelity driving simulator. In the third experiment, participants performed the eight tasks while driving an instrumented vehicle in a residential section of a city.
In each experiment, the tasks involved 1) a baseline single-task condition (i.e., no concurrent secondary task), 2) concurrent listening to a radio, 3) concurrent listening to a book on tape, 4) concurrent conversation with a passenger seated next to the participant, 5) concurrent conversation on a hand-held cell phone, 6) concurrent conversation on a hands-free cell phone, 7) concurrent interaction with a speech-to-text interfaced e-mail system, and 8) concurrent performance with an auditory version of the Operation Span (OSPAN) task. Each task allows the driver to keep his or her eyes on the road and, with the exception of the hand-held cell phone condition, hands on the steering wheel, so any impairment to driving must stem from cognitive sources associated with the diversion of attention from the task of operating the motor vehicle.
We used a combination of performance indices to assess mental workload, including reaction time and accuracy in response to a peripheral light detection task (the detection reaction task [DRT]: ISO, 2012), subjective workload measures from the NASA Task Load Index (NASA TLX: Hart & Staveland, 1988), and physiological measures associated with Electroencephalographic (EEG) activity and Event-Related Brain Potentials (ERPs) time-locked to the peripheral light detection task. We also obtained primary-task measures of driving in experiments using the driving simulator and instrumented vehicle.
We used these data to develop a rating system for cognitive distraction where non- distracted single-task driving anchored the low-end (Category 1), and the OSPAN task anchored the high-end (Category 5) of the scale. In-vehicle activities such as listening to the radio (1.21) or an audio book (1.75) were associated with a small increase in cognitive distraction, the conversation activities of talking to a passenger in the vehicle (2.33) or conversing with a friend on a hand-held (2.45) or hands-free cell phone (2.27) were associated with a moderate increase in cognitive distraction, and the speech-to-text condition (3.06) had a large cognitive distraction rating.
These findings can be used to help craft scientifically-based policies on driver distraction, particularly as they relate to cognitive distraction stemming from the diversion of attention to other concurrent activities in the vehicle. Some activities, such as listening to the radio or a book on tape, are not very distracting. Other activities, such as conversing with a passenger or talking on a hand-held or hands- free cell phone, are associated with moderate/significant increases in cognitive distraction. Finally, there are in-vehicle activities, such as using a speech-to-text system to send and receive text or e-mail messages, which produced a relatively high level of cognitive distraction. The data suggest that a rush to voice-based interactions in the vehicle may have unintended consequences that adversely affect traffic safety. |