Scientists in the US have shown that listening to a cell phone while driving was enough distraction to cause drivers to make the same type of driving errors as they would under the influence of alcohol.

The study is the work of neuroscientist Dr Marcel Just and colleagues at the Center for Cognitive Brain Imaging at Carnegie Mellon University in Pittsburgh, Pennsylvania, and is to be published shortly in the journal Brain Research.

Even if you are not talking, just listening to a cell phone conversation can significantly reduce the amount of brain activity associated with driving, said the researchers, who asked volunteers to drive on a simulator while they observed their brains using an MRI (magnetic resonance image) scanner.

Using cell phones while driving has been a matter of controversy for some time, but this is the first study to look at listening alone as a distraction.

Just and colleagues found that listening alone reduced brain activity associated with driving by 37 per cent. Based on driving simulator results, this would be enough to cause a driver to weave out of their lane, said the researchers.

“Drivers need to keep not only their hands on the wheel; they also have to keep their brains on the road,” said Just in a prepared statement.

Just and colleagues invited 29 volunteers to to use a driving simulator while inside an MRI brain scanner. The simulator gave them a winding road to drive on at a fixed but challenging speed. There were two conditions: undisturbed or while listening. While listening, the volunteers listened to statements and had to decide whether they were true or false, a similar level of cognitive processing as would be involved in a normal listening activity.

The researchers used the latest functional magnetic resonance imaging (fMRI) technology to measure second by second changes in brain activity in 20,000 places, each being about the size of a peppercorn, they said.

Compared to the undisturbed scenario, the listening while driving scenario showed a 37 per cent decrease in activity in the brain’s parietal lobe, the part of the brain that is associated with driving and processes sensory inputs that are important for navigation and spatial awareness. The occipital lobe, which processes visual signals, also showed reduced activity, said the researchers.

Using measures of performance on the simulator, the researchers observed that the driving while listening scenarios resulted in much poorer quality of driving. When in listening while driving mode the volunteers made more errors in lane discipline, such as deviating from the middle and hitting a guardrail.

The study suggests that hands free and voice activated cell phones do not go far enough to ease safety concerns because the distraction of listening would still remain.

The researchers said that other distractions such as listening to the radio, eating or talking to a passenger can also divert a driver, and although there is no evidence of how these distractions compare to listening to a cell phone, they suggest cell phones are different because, as Just explained:

“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.”

A passenger, on the other hand, because he or she is physically in the car with the driver, can see if anything urgently needs the driver’s attention and will stop talking, it is a situation that is less likely to put social pressure on the driver.

Just said the clear message of this study is that:

“Engaging in a demanding conversation could jeopardize judgment and reaction time if an atypical or unusual driving situation arose.”

He warned that:

“Heavy traffic is no place for an involved personal or business discussion, let alone texting.”

Previous studies had suggested that driving and listening used two differnt parts of the brain and could work independently of each other, thus allowing the driver to “multi-task” safely.

But this study suggests otherwise, said Just, it doesn’t matter how different the tasks are, the brain can only do so much at one time.

The study is an example of the new science of neuroergonomics that studies the match between technology and human ability by bringing together brain science and research on human-computer interaction.

Neuroergonomicists are starting to observe humans operating ships, cars, and other vehicles where the driver’s position is beginning to look more and more like the cockpit of an aircraft with all the technology interfaces that now exist.

Every additional device demands brain activity, increasing the likelihood that resources crucial for making fine judgements on the road are compromised.

If brain resource for safe driving is limited, then perhaps it should be devoted to paying attention to those devices that help the driver make these judgements, rather than the cell phone, iPod, CD, radio, or even DVD player.

“Drivers’ seats in many vehicles are becoming highly instrumented cockpits,” Just explained, “and during difficult driving situations, they require the undivided attention of the driver’s brain.”

“A decrease in brain activation associated with driving when listening to someone speak.”
Marcel Adam Just, Timothy A Kellera and Jacquelyn Cynkara.
Brain Research Article in Press (Accepted Manuscript).
Available online 19 February 2008.

Click here to see a full preprint issue of the study (from CMU Center for Cognitive Brain Imaging website).

Sources: Carnegie Mellon University press release.

Written by: Catharine Paddock, PhD