Picture a driver distracted by a passenger's joke or the ping of an incoming text. Oblivious to an obstacle ahead of him, he is pulled back to reality by an alert from his car's collision warning system.
After a few such incidents, would this driver be chastened into paying closer attention to the road? Or would he figure that he could chat or text even more since his trusty car is watching the road for him?
Neither, it turns out. A recent IIHS study based on observations of volunteers driving a Honda Accord with a combined forward collision, lane departure, blind spot and curve speed warning system found that receiving warnings neither discouraged nor encouraged distracting behaviors. That finding held for both teenagers and adults.
"We hypothesized that collision alerts might lead drivers to focus more closely on driving, but that wasn't the case," says the study's author, IIHS Senior Research Scientist David Kidd. "At the same time, fears that warning features might have the opposite effect appear to be unfounded."
To perform the analysis, Kidd looked at random video clips from each driver in two separate observational studies in which participants drove 2006-07 Accords equipped with the prototype warning system. One study included 108 adult drivers, all of whom drove with the warning system after an initial period driving without it. The second study included 40 16-17-year-old drivers, half of whom drove with the warning system after an initial period of driving without it and half who drove without it for the entire length of the study.
Having the warning system activated didn't make drivers more or less likely to engage in secondary behaviors in general or in any specific individual behavior such as talking with a passenger or using a cellphone, Kidd found.
On average, the 108 adult drivers and the 20 teen drivers who drove with the warning system were engaged in at least one secondary behavior in 46 percent of the clips. The most common behaviors were talking with a passenger, personal grooming, talking on a cellphone, and looking at or manipulating a phone or other device. The younger the driver, the more common distracting behaviors were. For example, 57 percent of clips of teen drivers had at least one distracting behavior, while the percentage was 39 percent for 60-70-year-old drivers.
Drivers were more likely to engage in secondary behaviors when the vehicle was traveling below 5 mph or stopped than when the vehicle was traveling over 25 mph. That finding is in line with a previous IIHS study that showed drivers were more likely to engage in distracting behaviors at red lights than in more demanding situations (see "Distracting behaviors are common at red lights, less so at roundabouts," March 31, 2015).
In the current study, the warning system didn't affect the speeds at which drivers engaged in secondary activities.
Although warning systems don't appear to improve driver behavior, they still have a big role to play in reducing crashes caused by distraction (see Status Report special issue: distracted driving, Oct. 24, 2014).
"Completely eliminating driver distraction isn't possible," Kidd says. "Warning systems that bring a driver's attention back to the road when a crash is imminent can help keep distraction from turning deadly."