Photo via Flickr / CC.
It’s pretty much conventional wisdom at this point that talking on your cell phone and driving is bad. Like, drunk driving bad. So cities and states are legislating accordingly banning cell phone use behind the wheel. But a new study asks: If driving while on your phone is so bad, why don’t crashes spike when cell phone use does?
Laboratory tests have proven that cell phones are distractions and the statistics indicate that distracted driving leads to crashes, but researchers at Carnegie Mellon and the London School of Economics looked at the results in the real world, and were surprised by what they didn’t find. Even when cell phone use spiked, car crashes didn’t correlate.
The study looked at cell phone data from 2005, before smartphones, when all we wanted was "free nights and weekends." As calls became free at 9 PM, people would start making more calls.
“We found the increase was pretty large–20 to 30 percent,” said study co-author Saurabh Bhargava, an economics professor at Carnegie Mellon.
In order to make sure that drivers were also making more calls, Bhargava and his team got data from a major US cell phone provider and restricted the data set to phone calls that had been filtered through multiple cell phone towers, which meant that the caller was moving, if not driving specifically. And this group also took advantage of making calls at night. “We conservatively estimate that for drivers the increase was at least 7 percent right at 9 PM.”
But the rate of crashes didn’t change as calls became free; it stayed consistent with how accident rates worked around 9 PM in the pre-cell phone era. So dial away, right?
Maybe not. “I think we all recognize that human attention is limited and cell phones can certainly occupy some of that attention,” Bhargava said. “I think there are few different ways to reconcile what we find to a lot of the experimental evidence.”
Bhargava speculates that those who are driving and talking at the same time might be compensating in other ways. “People might compensate or adjust to the dangers of cell phone use by driving more carefully or being very selective about when they make a call,” he said.
“Another potential explanation is that the type of drivers that tend to talk on their cell phones are the type that tend to engage in risky activities. Playing with the radio, talking to fellow passengers etc,” he said.
There is a slight selection bias going on in the study, though. If someone is willing to engage in the “risky activity” of talking on their cell phone while driving, it’s possible that they’re not the type to care about the cost of the phone call, which would just be taken off of your “monthly minutes” anyway.
Trying to imagine this study’s impact on legislation is sort of difficult—after all at this point talking on cell phone is probably the least-terrible thing you can do, and any laws that get phones out of people’s hands still has an intuitive logic. “A lot of the experimental evidence suggests that texting is far more dangerous–seven or eight times more dangerous than talking on the phone, and I share the intuition,” said Bhargava. “Our results speak very specifically to just talking on the cell.”
But understanding how and why cell phones change driving habits could impact how car accidents with drivers on phones are prosecuted, whether its a primary or secondary offense, and also just how and what should be banned, if banning is the way to go.