Just listening to a cell phone
conversation cuts a person's ability to concentrate on
driving by more than a third, a Carnegie Mellon
University neuroscientist told state lawmakers
The House Transportation Committee met Downtown to
gather information as it considers several legislative
proposals on restricting cell phone use by drivers,
Marcel Just, who directs Carnegie Mellon's Center for
Cognitive Brain Imaging, showed colorful images of brain
activity in a person driving in silence compared with
one listening to a cell phone conversation. Activity
dedicated to driving decreased by 37 percent when
"As you can see, they're fairly dramatic results,"
said Just, whose results will be published in an
upcoming issue of the scientific journal Brain Research.
His study is the first of its kind.
story continues below
Just had 29 licensed
drivers use a computer program and a joy stick to
navigate a winding road while blood flow to their brain
was monitored by functional magnetic resonance imaging,
or fMRI. The drivers listened to a person asking them
true or false questions through headphones, meant to
simulate a hands-free cell phone.
State Rep. Josh Shapiro, D-Montgomery, has proposed a
law banning drivers from using handheld cell phones and
pressed Just about whether hands-free phones that use
headphones or speakers are better.
Because of limited space in the fMRI machine, Just
said, he wasn't able to measure the effect of
text-messaging or using a handheld phone. He speculated
they would add another distraction and brain activity
dedicated to driving would likely further decrease.
"I'd rather the person use hands-free rather than
handheld," he said.
Just said talking passengers likely aren't as
distracting to drivers as a cell phone conversation
because passengers can see when traffic is difficult and
The committee also heard testimony from groups
including the Center for Automotive Safety Research at
the Virginia Tech Transportation Institute and AAA.
Committee Chairman Joe Markosek, D-Monroeville,
pointed out that no states have completely banned cell
phone use while driving. He said compromises -- such as
allowing hands-free devices -- would have to be made to
get some restrictions in place.
"We're probably going to fall somewhere in the
middle," he said. "It's our goal ... to get some
Simply requiring that studies such as his be
presented at driver education classes could convince
people not to risk using a cell phone while driving,