
Using a hands-free phone or other technology while driving can keep you distracted for up to 27 seconds after you’ve finished the call or changed the music, according to research published Thursday by the non-profit AAA Foundation for Traffic Safety.
Even while driving at a relatively slow speed of 25 mph, that 27 seconds would take you the distance of almost three football fields, the foundation points out.
“The lasting effects of mental distraction pose a hidden and pervasive danger that would likely come as a surprise to most drivers,” said Peter Kissinger, the foundation’s president and CEO, in a released statement. “The results indicate that motorists could miss stop signs, pedestrians and other vehicles while the mind is readjusting to the task of driving.”
Traffic safety experts have long warned that hands-free devices do not eliminate the risk of having an accident caused by distracted driving — and may even increase it because drivers mistakenly believe that such behavior is safe.
All of us — let me repeat, all of us — need to be in less denial. For distracted driving — whether it involves talking on a cell phone, texting, eating or using in-vehicle technologies — has become a major public health problem. Each day in the U.S., more than nine people are killed and more than 1,100 are injured in crashes involving a distracted driver, according to the Centers for Disease Control and Prevention (CDC).
Those are all tragedies that could have been prevented.
Two studies
The AAA Foundation’s new research, which involved two separate studies, was led by University of Utah neuroscientist David Strayer, a well-known expert in this field. One study examined the impact of three different “personal assistant” smartphone systems (Apple’s “Siri,” Google’s “Google Now” and Microsoft’s “Cortana”) on the mental concentration of 65 experienced drivers. The other study did the same for the hands-free technologies offered in 10 different 2015 vehicles. That study involved 257 drivers.
For the study, participants drove around a 2.7-mile route in a Salt Lake City neighborhood at speeds that never exceeded 25 mph. They wore a head device with LED lights that flashed every 3 to 5 seconds near the edge of their left eye. They were instructed to press a switch each time they saw the lights flash, an action that indicated how distracted they were.
Strayer and his colleagues rated mental distraction in both studies on a 5-point scale, with 1 representing mild distraction (the equivalent of listening to the radio or an audiobook) and 5 representing a very high level of distraction (such as taking a challenging scientific test).
The AAA considers any mental distraction rated 2 or higher as being potentially dangerous for drivers.
Key findings
The smartphone study found that manipulating the phone by voice command to place a call, select music or send text messages “was associated with a significant increase in driver distraction, compared to just driving.”

All three smartphone systems had distraction ratings well above AAA’s safe level, although Google’s system performed the best, with a rating of 3.3, followed by Apple’s (3.7) and Microsoft’s (4.1).
The distraction caused by these technologies lingered for up to 20 seconds after the driver finished interacting with the device.
All 10 different voice-activation systems in the second study were also associated with unsafe levels of distraction — and it wasn’t because the drivers were unfamiliar with them. For even after the drivers were given time to practice using the systems, the ratings improved only slightly.
The systems with the lowest distraction ratings belonged to the Chevy Equinox (2.37) and the Buick LaCrosse (2.43), while the system with the highest (most distracting) rating belonged to the Mazda 6 (4.57).
The study found that many of these voice-activation systems place much greater demands on drivers’ mental energy than typical cell phone conversations (which earlier research by the AAA Foundation rated 2.3 on the same scale).
Furthermore, interacting with the voice-activation systems had “residual” cognitive costs that kept the drivers distracted for up to 27 seconds after terminating a call or making their music selection.
‘A growing safety problem’
“The massive increase in voice-activated technologies in cars and phones represents a growing safety problem for drivers,” said Marshall Downy, the president and CEO of AAA, in the released statement.
“Given that the impairing effects of distraction may last much longer than people realize, AAA advises consumers to use caution when interacting with these technologies while behind the wheel,” he added.
You can read both studies on the AAA Foundation for Traffic Safety’s website. The organization has also posted a video that shows study participants attempting to drive safely while using various hands-free technologies.
Remember: That’s you behind the wheel, too.