O P I N I O N
Although it is becoming more and more accepted that driving while talking on a cell phone is hazardous, most jurisdictions are making handheld phone use illegal while allowing hands-free phone use. To determine if this unequal treatment by the law was justified, we examined the scientific literature exploring the effects of hands-free and handheld cell phone use on driving and driving-related activities with two questions in mind:
- Is it save to use a hands-free cell phone while driving?, and
- Is there a safety difference between hands-free phone and handheld phone?
To answer these questions, we reviewed the scientific literature comparing the effects of cell phone type (hands-free and handheld) on driving or driving-related activities. Two large-scale studies of actual accidents found that talking on a cell phone increased the risk of having an accident by a factor of four. Importantly, in both studies this increased risk was unaffected by whether the phone was handheld or hands-free. Experimental studies manipulate the type of phone being used during driving and include a control condition without phone use. These studies vary in the degree to which the driving task resembles real driving (fidelity) and range from actually driving a car, driving in a simulator and performing tracking tasks that share many of the real-time attributes of driving. Regardless of fidelity, the studies show that talking on the phone, whether handheld or hands-free, has negative impacts on driving or driving-related activity and causes robust delays in the speed of responding to occasional target events (meant to represent a car breaking in front of the driver or a person or object suddenly appearing in the path of the vehicle).
Importantly, in agreement with the studies of real-world accidents, using a hands-free phone was rarely found to be safer than using a handheld phone. Some studies found that drivers compensate, by slowing down a bit, for the risks of cell phone use when using a handheld phone. This compensatory slowing was rarely observed when using a hands-free phone. This failure to compensate may make using a hands-free phone even more dangerous.
The evidence, then, shows that it is not safe to use a hands-free cell phone while driving and there is no safety advantage for the hands-free phone (there may even be a disadvantage due to the lack of compensation). With such evidence at hand why do our lawmakers fail to outlaw hands-free cell phone use while driving? And why does the public resist such legislation? The following frequently asked questions are often offered as reasons. We hope that by answering them we will help shift attitudes and policy in the direction of safer, less distracted, driving.
Q: Isn't talking on a hands-free phone just like talking to a passenger in the car?听 Surely we aren't going to outlaw that!
A: Talking to a passenger is different from talking on a cell phone. One important difference is that a passenger in your car and you share the same situational awareness; somebody you are talking on a cell phone has no awareness of the difficulty of your driving task (or even that you are driving at all). It is more likely that a passenger will pause a conversation as appropriate to avoid interfering your driving. Conversely, if your response in a conversation is delayed because of a driving maneuver you may be perceived as rude or incommunicative when your conversation partner is on the phone but the partner in the car will, based on their perception of the situation, understand.
听听听 听
Q: Isn't it simply common sense that when we drive a two-ton vehicle we should be paying attention? You shouldn't have to legislate common sense.
A:听 If common sense could be relied upon we would not need laws banning drinking and driving. The fallibility of common sense is demonstrated by the conflict between scientific evidence about the danger of hands-free phone use and legislative practice that rarely bans it.听 听
听
Q: Isn't it pointless to pass a law that may be difficult for the police to enforce?
A: Quite the contrary. Laws banning handheld phone use while permitting hands-free use are perpetuating the 鈥渃ommon sense鈥� but false belief that using a hands-free phone while driving is safe. The legality of its use may even contribute to the failure to compensate by slowing down when using a hands-free phone. Challenges to enforcement, therefore, must not be a consideration in the formulation of safety legislation. Moreover, these challenges may be ameliorated through technological solutions (such as equipment that detects phone use in a moving vehicle).
Q: When I drive while talking on my hands-free phone my two hands are available for steering. Why then is this dangerous?
A: Everyone realizes that we drive with our hands and feet. Our hands and feet are controlled by our minds which also perform the continuous tracking, speeded detection and complex decision making that characterize driving. Since we drive with our minds, it is unwise when driving to allocate significant portions of our limited mental capacity to activities unrelated to driving. The sound advice: 鈥淜eep your mind on the road鈥� is simply inconsistent with carrying on a cell phone conversation.
Ray Klein is the chair of the Department of Psychology at 黄色直播. PhD student Yoko Ishigami was awarded the top student paper for her research into hands-free cellphones at the conference of Canadian Multidisciplinary Road Safety Professionals in 2008.