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Cell Phones and Driving: The Myth of "Hands-Free" Safety
2/3/2002
 Television and radio commercials readily endorse the driver safety benefits of hands-free phones. Auto manufacturers are offering hands-free cellular phones as a factory option on their latest models. Congress is even contemplating restrictions on hand-held cell phone use for drivers, but do not necessarily extend the restriction to 'hands-free' users. So, hands-free phones must be safer than their hand-held counterparts, right' A National Safety Council Study conducted by the University of Utah (published in the November 2001 issue of American Psychology Society) suggests the margin of safety afforded by hands-free cell phones is more myth than fact.
The National Safety Council estimated there were more than 117 million cell phone subscribers in the United States by in mid-year 2001. It is estimated that up to 60% of cell phone use by these subscribers occurs while users are driving.
There's little doubt that cell phone use creates a distraction for drivers, but these distractions have often been associated with the operation of the phone (e.g., dialing numbers, holding the phone, etc.). Consequently, the ease of use linked to voice-activated, hands-free phones has been perceived as lessening the distractions associated with cell phone use.
The National Safety Council study debunks this conventional wisdom. It's not the phone that causes the distraction, but the act of two-way communication itself.
The study utilized 64 volunteers (32 females, 32 males) with 'normal or corrected-to-normal vision' who were randomly assigned to control groups that listened to the radio, listened to a book-on-tape, operated a hand-held cell phone, or operated a hands-free cell phone. While listening, participants sat at a computer terminal and operated a joystick to align a curser with a moving target, the target would turn green or red. Subjects were instructed to ignore the green signal, but to toggle a button on the joystick as soon as the target turned red. The purpose of this 'dual task' experiment was to calculate each subject's reaction time to acknowledge a red target.
Preliminary results indicated no difference in reaction times between hand-held and hands-free cell phone users. The 'miss rates' (or probability of missing a simulated traffic signal) increased when subjects were engaged in conversations on cell phones. There was no subsequent performance deficit in the radio or book-on-tape groups.
The principle findings of the study indicated that cell phone users (both hand-held and hands-free) who engaged in phone conversations 'missed twice as many simulated traffic signals as when they were not talking on the cell phone'. Of the signals the cell phone test subjects did detect, reaction times were much slower than those observed in the other test groups.
The conclusion reached by the researchers suggests 'hands-free devices are not likely to reduce interference from the phone conversation,' because the interference is attributed to the attention processes associated with conversations, not the operation of the cell phones.
More studies will occur regarding the use of cell phones while operating motor vehicles. However, the National Safety Council study offers evidence that drivers could be doing themselves a great favor by resisting the temptation to make or take calls while driving.
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