distracted driving
March/April 2016

In-Vehicle Mental Distraction

Research shows mental distraction can last as long as 27 seconds after using voice commands to make a call, send a text, or change the music

BYRob Bhatt
If you’re like most people, you probably need a few moments to mentally focus on your next task after you end a phone call or send a text message, even from a hands-free system. But what if your next task required you to avoid a vehicle or pedestrian that entered your path? Would you be able to properly react when the traffic light you were waiting at turned green? New scientific answers to these questions may surprise you. 
 
27 Seconds to Refocus
In its latest look at in-vehicle mental distractions, a University of Utah-based research team led by professor David Strayer and sponsored by AAA Foundation for Traffic Safety discovered test subjects needed up to 27 seconds to fully restore their mental focus on driving after ending a call or texting from voice-controlled systems in their cars. These lingering distractions, referred to as “residual costs,” were determined by measuring participants’ reaction times to potential hazards while conducting such interactions as they drove on suburban roads.
 
“These residual costs are notable,” Strayer says. “At 25 mph, a vehicle would travel up to 988 feet (the approximate length of three football fields) before the residual costs completely dissipate. These findings have implications for people who think it’s safe to dial or send a text message at a stoplight, because the distractions from these interactions are likely to persist after the light turns green.”
 
Strayer’s study analyzed distraction levels resulting from the use of voice-controlled information systems available in 10 vehicles and on three smartphones. Among the vehicles, the Chevy Equinox had the lowest, or best, distraction rating, while the Mazda 6 had the highest, or worst, rating. Of the smartphone systems, Google Now performed best, followed by Apple Siri and Microsoft Cortana, and using the latter three systems to send text messages significantly increased cognitive distraction levels. 
 
“Developers should aim to reduce mental distractions by designing systems that are no more demanding than listening to the radio or an audiobook,” says AAA President and CEO Mike Tully. “We advise consumers not to use these new technologies while behind the wheel, even at a stop sign or red light, given the high risk that distraction may last much longer than people realize.” 
 
 
Additional research notes: Based on the driving performance of 257 participants divided into three age groups (21 – 34, 35 – 53, and 54 – 70), the researchers determined that in-vehicle systems placed greater mental demands on older drivers than on younger drivers. After an initial analysis, participants kept their cars for a week before returning for a second round of testing. Even after familiarizing themselves with their vehicles’ information systems, participants showed only marginal improvement in driving performance, leading researchers to conclude that such distractions “cannot be practiced away.”
ROB BHATT is the editor of Western Journey magazine, published by AAA Washington.
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