Sayer is co-author of a Transportation Research Institute study released in 2005 entitled “The Effects of Secondary Tasks on Naturalistic Driving Performance.”
What were the worst distractions? “First, don’t call what we measured distractions. Distractions are cognitive, and you can’t measure what a person is thinking,” Sayer says. “We measured driving performance while people were engaged in secondary tasks — tasks other than driving.”

Secondary tasks considered in the research included cell phone use, talking to passengers, eating, drinking, grooming, smoking, and using in-car systems such as the radio or CD player.

The test placed sophisticated video surveillance and data acquisition systems inside the cars to measure changes in driving performance during secondary tasks. In evaluating the video and the data collected during the test period, the researchers “learned that doing something other than driving basically always has a negative effect on performance,” Sayer says. “For instance, we found that cell phone conversations caused drivers to move back and forth in their lane, but the drivers did stay in their lanes, more or less in the center. But it was a lot of work to do that. Drivers using cell phones did not vary their speeds very much.”
According to the finished report, talking with passengers had much the same effect on driving as talking on the cell phone.

A report by the National Highway Traffic Safety Administration (NHTSA) and the Virginia Tech Transportation Institute released in April found that cell phone calls are the most common distracting behavior in which drivers engage. While the study implicated cell phones in many crashes, the problem was not talking or listening it was dialing.

Commenting on the NHTSA study, Michael Gardner, director of intelligent systems research with Schaumberg, Ill., based Motorola, Inc., says: “It showed that when you are driving while pushing buttons on a cell phone held in your hand, the risk of an accident is 2.4 times greater than baseline or average driving (with no distractions). But if you are holding the phone to your ear and having a conversation and have your other hand on the wheel, it is no riskier than baseline driving.”

According to Gardner, more than 70 formal research studies have explored the problem of distracted drivers in recent years. Until the NHTSA study, however, no research had indicated that talking on the phone was basically the same risk as normal driving.

Nevertheless, no one disputes the claim that drivers must learn to control the many distracting behaviors characteristic of modern motor vehicle operation. But what is the most effective means to that end? Leg-islation aimed at cell phones certainly does not address the overall problem of distracted driver behavior. What about grooming, eating, and using the CD player?