Despite the growing acceptance of the idea of “multi-tasking”, Center studies from the early 2000s suggest that the human brain has a finite amount of space for tasks requiring attention.  People performing two demanding tasks simultaneously do neither one as well as they do each one alone.  (No doubt, most of us knew this already). Marcel Just, a psychology professor and co-director of the Center said that while this study “did not examine the brain activity of people who were driving cars and conversing, it used tasks that engage[d] similar brain regions.”  But “plans [were] under way to study the brains of people… using driving simulators while someone is talking to them.”

 

In early March 2008, in the context of Pennsylvania state legislative committee hearings considering several bills that would, among other things, prohibit drivers with learner's permits from using cell phones and ban text messaging and mandate hands-free phone devices for all drivers, Dr. Just said that the Center’s latest studies indicated that such a bill is “just not enough.”  For the first time studies showed that listening alone “reduces by 37 percent” the amount of brain activity associated with driving causing subjects using driving simulators to, for example, weave out of their lanes.

 

The findings, to be reported in an upcoming issue of the journal “Brain Research”, reportedly show 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,” said Dr. Just. He added that, “there are reasons to believe cell phones may be especially distracting.  Talking on a cell phone has a special social demand, such that not attending to the cell conversation can be interpreted as rude, insulting behavior,” he noted.  A passenger, by contrast, is likely to recognize increased demands on the driver’s attention and stop talking. Good point.

 

This latest study involved 29 volunteers using a driving simulator while inside an MRI brain scanner.  They steered a car along a virtual winding road at a fixed, challenging speed, either while they were undisturbed, or while they were deciding whether a sentence they heard was true or false.  Scientists had previously suspected that the “driving” and “listening” networks could work independently on each task.  But Dr. Just said, “this study demonstrates that there is only so much that the brain can do at one time, no matter how different the two tasks are.”

 

Most of the discussion so far is theoretical in terms of traffic safety. The down to earth question is “how many collisions actually involve a driver using a cell phone?”  The records are available for this analysis.