It takes almost half a minute for a human driver to start fully concentrating on the road again after using his or her phone or an inbuilt infotainment system while driving, researchers have found.
Even hands-free interfaces such as voice based systems used by Microsoft Cortana, Apple Siri or Google Now have proved to be highly distractive in tests conducted by University of Utah researchers.
"Just because these systems are in the car doesn't mean it's a good idea to use them while you are driving," said University of Utah psychology Professor David Strayer, author of two new studies conducted for the AAA Foundation for Traffic Safety.
"They are very distracting, very error prone and very frustrating to use. Far too many people are dying because of distraction on the roadway, and putting another source of distraction at the fingertips of drivers is not a good idea.”
The researchers investigated the impact of voice-dialling, voice-contact calling and music selection on drivers’ attention. They examined systems in ten vehicles from model year 2015 and ranked them based on how much distractive they appeared to be. The worst rated was the infotainment system of Mazda 6, which was considered very highly distracting. Further six systems were seen as highly distracting and the remaining three as moderately distracting.
The tests were conducted at speeds of 25 mph (40 km/h) and the researchers were shocked to find that it took up to 27 seconds to regain full concentration after engaging with some of the most distracting systems.
In 27 seconds a car travelling at 25 mph covers the length of three football fields.
The use of moderately distracting systems affected the drivers’ attention for 15 seconds.
"Most people think, 'I hang up and I'm good to go,'" Strayer said. "But that's just not the case. We see it takes a surprisingly long time to come back to full attention. Even sending a short text message can cause almost another 30 seconds of impaired attention."
Generally believed to be safer to use in a car than conventional touch-based interfaces, voice-based control systems were found especially distractive for older drivers.
"The voice-command technology isn't ready," said Joel Cooper, a University of Utah research assistant professor of psychology and co-author of the new studies. "It's in the cars and is billed as a safe alternative to manual interactions with your car, but the voice systems simply don't work well enough."
The researchers were critical of the fact that entertainment systems are being deliberately installed into cars, allowing the drivers to use Facebook, Twitter or FaceTime while driving instead of keeping them focused on the road.
Distraction is a major cause of traffic accidents. According to the US Department of Transportation, 3,154 people died and 424,000 were injured in the US in 2013 in car crashes caused by driver distraction.