When University of Illinois researchers had people talk on a cellphone while doing computer tasks designed to simulate driving, they found that hands-free phones were just as distracting as the handheld version.
Now, they've repeated the experiment – and the results – in an actual car.
Don't worry. Tate Kubose, a postdoctoral researcher at the UI, psychology Professor Art Kramer and colleagues didn't make the yackety-driver-laden streets of Champaign-Urbana any scarier than they already are.
Participants in the study – college students – drove and chatted in a "high-fidelity" driving simulator in the basement of the UI's Beckman Institute that includes a real Saturn sedan, albeit minus the engine.
Although the car, thankfully, is anchored to the floor, it works pretty much like it would outside. It's surrounded by movie screens, creating kind of a Saturn-sized IMAX theater or the ultimate 3-D computer driving game.
Press the gas pedal and the car appears to move forward. Turn right and the scene outside the windshield moves in that direction. Hit the brakes and ... you get the idea. The researchers can even simulate a windy day, making it harder to stay on the virtual road.
"It's a real car; it operates just like a car," Kramer said. "I think it's fairly realistic."
The simulator also is equipped with cameras and a variety of sensors that allow researchers to collect a stream of data ranging from steering wheel movements to where a subject's attention is focused.
With abundant evidence that verbal tasks like talking on the phone impair driving performance, the UI researchers set out to explore what aspects of a conversation – the talking or the listening – are more detrimental.
Their conclusion: both. Participants in the study were about as likely to get too close to a truck projected in front of them and sometimes hit it, whether they were on the producing or the consuming end.
In the earlier study, Kramer and his collaborators found that hands-free cellphone conversations made both younger and older drivers less likely to detect changes on the road ahead, and the older drivers slower to act when they did detect meaningful changes.
In the new study, the participants, in effect, gave or got directions while driving. Control groups also operated the simulator without the phone and used the phone without driving the simulator.
When driving, the subjects, who wore a telephone-like headset, were charged with staying in their lane and maintaining a two-second difference between their vehicle and traffic ahead.
The directional tasks involved answering questions about the location of familiar buildings on campus or checking statements made by someone on the other end of the phone about the location of the buildings.
The students, 100 in all, were given tasks requiring "spatial reasoning" intentionally. Other studies have shown that activities like giving directions over a cellphone are more likely to interfere with driving, which also is a highly spatial activity.
That the drivers had trouble maintaining their distance from other traffic, and sometimes failed entirely, wasn't unexpected. But the finding that talking and listening to a conversation are almost equally impairing was a surprise, Kramer said.
Before the experiment, the idea was that since speaking is the more complex task, it's more likely to disrupt other tasks performed at the same time, like driving.
Likewise, listening to the radio doesn't have the detrimental effect of listening on the phone. The researchers don't know why at this point, but Kubose said that conversation may involve a denser flow of information requiring more concentration to process.
"You can tune out (the radio) easier," he said.
The results appear in the latest issue of the journal Applied Cognitive Psychology. Researchers Kathryn Bock, Gary Dell, Susan Garnsey and Jeff Mayhugh also worked on the study.
Next, the UI researchers plan to test older drivers, beginning drivers 16 to 18 and drivers who are non-native English speakers.