Thought Bytes...
January 2003

Cell phones: is hands free risk free?

You are driving along a busy street. Cars are parked along the sides. Traffic lights are ahead with people anxious to cross at the cross walk. The light turns yellow and you must make a split second decision whether to accelerate to make it through the light or try to stop in time.

Scenario #1: You are alone in the car and the radio is playing. For a few seconds you tune out the information or music while you make your decision and act on it. This is fine because the radio doesn't have expectations for you to reply. We have learned that radios are background noise and have no feelings one way or the other about us paying attention to them.

Scenario #2: Your friend is in the passenger seat and you have been having a pleasant conversation. The passenger typically keeps a moderate amount of attention on the road, so when the light changes, she is also (possibly subconsciously) making the decision whether to proceed or stop. This is why passengers try to put their foot through the floorboards sometimes. For a few seconds, the conversation stops while you make the decision and act on it.

Scenario #3: The kids in the back are having a fight. In fact, they are screaming bloody murder. You glance in the rear view mirror to see what the problem is. Someone at the cross walk starts to step out. You have to swerve to avoid them because you were unable to make the decision to stop at the light because you were attending to the noise in the back seat. The sudden movement of the car momentarily makes the kids quiet.

Scenario #4: You are alone in the car but carrying on a conversation with a client on the cell phone. You are trying to carry on a meaningful conversation - the big sale could depend on this conversation. Someone at the cross walk starts to step out just as the client starts to say something very important. You know that what he has to say could make or break the sale, so you pay careful attention to it. The person on the other end of the phone has no idea about the traffic conditions or your stress level. He doesn't know that he needs to stop talking for a second or two so that you can negotiate this traffic light and crosswalk safely. Hopefully the person in the crosswalk has good peripheral vision and can hear the car approaching.

While each of these scenarios deals with the issue of auditory inputs, there is a different social context for each of them. The radio can be ignored without hurt feelings. The passenger will stop talking for a moment or realise that you have stopped talking during the stressful driving conditions. The children likely won't actually kill each other so they can be ignored for a few seconds without serious harm or hurt feelings. But, the client on the other end of the phone has no idea that they are not your primary focus, even for a moment. In our society, phones have become the means by which we convey that someone has something important to say (unless you can march into their office to say it).

Cell phones are incredibly useful, there is no disputing that. Early reporting of traffic incidents has saved lives. Families have been comforted by knowing that someone will be late. Extra work has been done while waiting in traffic jams. The problem lies with the combination of cell phone use and motion. When we are in motion, there are so many stimuli being perceived by the eye that the brain must filter and sort to determine what is required to perform the task. We can only attend to a limited number sensory inputs at any given time. When the system is overloaded, additional information is simply ignored by the brain.

Making cell phones hands free (i.e. by using a headset) may eliminate the risks associated with limiting neck / torso rotation and blocking some peripheral vision. But, it does not compensate for the brain's ability, or inability, to cope with multiple sources of information.

For another good summary of the issues, take a look at this web site: www.ama.ab.ca/mission_possible/ news_releases/n020408.html.

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