Hands-free operation no cure for driver distraction

By Bill Holloway

In a report released last month by the non-profit AAA Foundation for Traffic Safety, researchers at the University of Utah found that using even the least distracting voice-activated in-vehicle information systems (IVIS) generates a greater cognitive distraction than a typical cell phone conversation, and that the use of these systems continues to distract drivers for nearly 30 seconds after they have finished interacting with the system. The researchers tested 127 male and 130 female subjects ranging from 21 to 70 years of age on 6 different tasks, including calling contacts, dialing phone numbers, and selecting music while they were driving.

Participants used one of 10 different 2015 model year vehicles equipped with IVIS and were tested driving a 2.7 mile course on suburban style residential streets. Participants’ cognitive workload was assessed in three ways: a head-mounted detection response task (DRT) device, video cameras mounted in the vehicle to record signs of distraction during the drive, and through a series of subjective questions following their completion of the task. The cognitive workload required to perform each task was rated on a scale from 1.0, which was the baseline level for driving with no additional task, to 5.0, the level associated with driving while completing a memory and mathematical problem solving task. Following their initial test, participants were allowed to take home their test vehicle to use for five days before the second test.

Overall, the cognitive workload associated with using IVIS averaged 3.34 on the 5-point scale, ranging from 2.37 to 4.57 for different vehicles. Older drivers experienced a greater cognitive workload than younger drivers while using IVIS systems, and practice using the systems before the second test did not reduce the level of distraction associated with the systems. After interacting with IVIS, drivers took an average of 27 seconds to return to the baseline level of cognitive workload associated with driving alone. Not surprisingly, more intuitive, less error-prone IVIS systems with shorter task durations were less distracting to drivers than more complex, time-consuming, and error-prone systems.

This study highlights the potential for driver distraction from hands-free devices. State laws, however, have not caught up. While 37 states and the District of Columbia ban all cell phone use by novice/young drivers, and many states prohibit texting and the use of hand-held cell phones for all drivers, no states have general prohibitions on the use of hands-free phones or other devices while driving.

As noted in the New York Times, hands-free systems are promoted to consumers as a safer alternative to using hand-held phones and are profitable add-ons for carmakers. As these systems become more common features in cars, it will likely become more difficult to put the genie back in its bottle.

Bill Holloway is a Transportation Policy Analyst at SSTI.