In fact, a study on the impact of auditory distractions on visual attention, authored by U of T Professor Ian Spence, suggests that the comparatively unobtrusiveness of voice-activated hands-free cell phone calls is risky driving behavior.
In one of the study’s tests, Spence and a team of researchers asked subjects to identify the random location of an object in visual clutter displayed on a computer monitor while performing a set of increasingly difficult tasks. The most-demanding required subjects to take the last letter of a presented word (e.g. apple) and speak another word beginning with that letter (e.g. elephant).
Subjects who completed the test of visual attention coupled with the listening/speaking tasks were as accurate as those who completed the visual test in silence. However, they responded much more slowly as the difficulty increased – as much as one second slower with the most demanding tasks.
“At 50 kilometres per hour, a car travels 13.9 metres in one second,” Spence said. “A driver who brakes one second earlier than another driver to avoid a collision, will either prevent it completely or be traveling more slowly when it occurs, lowering the probability of severe injury or fatality. A delay in braking by as much as one second presents a significant threat to safe driving and casts doubt on the belief that hands-free voice-controlled devices reduce driver distraction.”
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