BACKGROUND: Backing up studies that show that drivers who use cell phones are more likely to have accidents, recent experiments by scientists at the University of Kansas show that observers engaged in a verbal task have a limited spatial attention window. The reason? They're less aware of incoming visual "cues."
WHAT THEY FOUND: Participants in the experiments were able to perform a simple task quite easily. But when half the group was asked to take on an additional verbal task, their ability to perform the first task was hindered. This indicates that even with the wide availability of hands-free devices for cell phone use in the car, there is still a significant risk involved when driving and talking on the phone at the same time.
THE PROBLEM: In the U.S., more than 190 million people used cell phones as of June 2005, compared to only 4.3 million in 1990. Studies have shown that motorists who use cell phones while driving are four times as likely to get into serious accidents. This happens in part because (a) people must take their eyes off the road momentarily while dialing, and (b) they become so absorbed in their conversations that it reduces their ability to concentrate on driving.
SPEECH AND THE BRAIN: Speech is a very complex function. There are two primary areas of the brain associated with speech: "Broca's area," located in the left frontal cortex, and "Wernicke's area," located further back and lower in the left temporal lobe. But scientists suspect other parts of the brain are involved as well. When we speak, we select words according to what we think the person we're talking to will understand. We activate the sounds for each word, and put them together in a sentence. We also choose which words to emphasize and how to pronounce them. All this information is processed by the brain and translated into movements of the mouth, jaw, tongue, palate, and voice box, among other areas.
The Human Factors and Ergonomics Society contributed to the information contained in the TV portion of this report.