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Sept. 3: Media Advisory: Carnegie Mellon Neuroscientist Uses Brain Imaging To Show Why Cell Phones Distract Drivers


Shilo Raube

Media Advisory: Carnegie Mellon Neuroscientist Uses
Brain Imaging To Show Why Cell Phones Distract Drivers

fmriWho: Marcel Just, the D.O. Hebb Professor of Psychology and director of the Center for Cognitive Brain Imaging at Carnegie Mellon University.

What: Dialing, texting and otherwise using a cell phone is a distraction for drivers and is causing many legislatures to consider laws restricting cell phone use in cars. In August, the U.S. Secretary of Transportation announced an upcoming summit for lawmakers and experts to discuss driving distractions and whether banning or limiting cell phones while driving is necessary.

According to Carnegie Mellon neuroscientist Marcel Just, simply listening to someone speak on the other end of a cell phone is enough to impair driving. Just and his colleagues used functional magnetic resonance imaging (fMRI) to study volunteers using a driver simulator. When they were listening to a sentence, they were more likely to weave in their lane than when they were driving undisturbed. Furthermore, the fMRI scans showed that listening to someone speak while they were driving reduced by 37 percent the amount of brain activity associated with driving, compared to driving alone, as shown in the accompanying graphic. This decrease in available brain resources can cause drivers to commit the same types of driving errors that can occur under the influence of alcohol.

Another study from Just's laboratory showed that subjects could not willfully ignore someone speaking to them; the processing of a spoken message was so automatic that it could not be gated out, and continued to affect the brain activation associated with a second concurrent task. This study shows the dangers of cell phone use by drivers can not be overcome by strategic control of one's attention.

Just's research shows that making cell phones hands-free or voice-activated is not sufficient in eliminating distractions to drivers. "Drivers need to keep not only their hands on the wheel; they also have to keep their brains on the road," Just said. "The clear implication of our work is that engaging in a conversation could jeopardize the judgment and reaction time if an atypical or unusual driving situation arose. Driving in quick-moving traffic is no place for an involved personal or business discussion, let alone texting."

Why: Just is a pioneer in using brain imaging to discover how humans perform mental tasks and has testified in front of the Pennsylvania General Assembly's House Transportation Committee on the dangers of hand-held phones and driving. His brain research also includes identifying the "team play" among different brain areas — a theory that explains how the brain compensates for damage from injuries such as stroke by recruiting back-up players. Additionally, Just and his colleague Tom Mitchell used brain imaging to identify the content of thoughts of concrete objects, being able for the first time to read the minds of people in their scanner.  A January 2009 "60 Minutes" report featured Just and Mitchell  demonstrating and explaining their thought identification work.

Contact: Phone or live, on-camera interviews with Just can be scheduled by contacting Shilo Raube at 412-268-6094 or

Listen to Just explain research showing why cell phones distract drivers in this podcast.


The above graphic depicts a brain that was scanned using functional magnetic resonance imaging (fMRI).