Cell Phones and Driver Distraction

Operating a motor vehicle is an activity engaged in by more than one billion people on an annual basis. Given that each year there are more than one million fatalities worldwide associated with motor vehicle accidents, driving represents one of the more risky activities undertaken on a regular basis by adults between the ages of 25 and 65. Estimates suggest that as many as 80% of accidents on the roadway are the result of some type of driver distraction, and it has been noted that one of the basic road errors is a failure to see and react to another road user in time. Driver distraction associated with visual processing can be divided into two general categories: Situations where drivers fail to look at roadway hazards in the driving environment (i.e., failures to look or fixate upon an object) and situations where drivers look at objects in the driving scene, but show degraded processing of the driving environment because attention is directed elsewhere (i.e., failures to see or attend to the object). This entry describes the relationship between cell phones and driver distraction.

Driver distraction associated with a failure of visual processing can be attributed to situations where drivers fail to direct their eyes to hazards in the roadway. This source of impairment can be the result of distractions from outside the vehicle (e.g., an electronic billboard with sudden onsets or movement that results in a reflexive orientating of the eyes to the billboard) or to distractions within the vehicle (e.g., dialing or text messaging on a cellular phone). In both situations, driving is impaired because the eyes are diverted from the roadway and the information necessary for the safe operation of the vehicle is not fixated on for a sufficient duration to allow for its processing. This results in a source of driver distraction wherein the driver fails to look at critical information in the driving environment. Research indicates that the concurrent performance of ancillary visual tasks often compromises driver safety; however, some drivers are more impaired than others. Compared with more experienced drivers, novice drivers are less able to interleave the performance of a concurrent visual task with driving. For example, novices tend to allocate longer epochs of visual processing to a secondary task than do more experienced drivers who exhibit frequent and short glances between the two tasks. In sum, the first source of distraction occurs if the driver does not look at an object, and thus, he or she cannot see and react in a timely fashion.

Driver distraction can also be caused by attention being diverted from driving to some other [Page 240]activity (e.g., a cell phone conversation), resulting in a form of inattention blindness. In such cases, critical information in the driving environment may be fixated upon, but the driver does not “see” the information because attention is directed elsewhere. For example, when drivers converse on either a Handheld or hands-free cell phone, they fail to subsequently recognize as much as 50% of the information that they would have recognized had they not been conversing on a cell phone. In addition, the impaired recognition is equivalent for both items of high and low relevance to safe driving, suggesting that there is little or no semantic prioritization of the information that is impaired by the cell phone conversation (i.e., drivers are as blind to a billboard on the side of the road as they are to a pedestrian standing on the curb). Moreover, recordings of brain activity indicate that cell phone conversations suppress the initial registration of information in the driving scene. In particular, the amplitude of the P300 component of the event-related brain potential elicited by imperative events in the driving environment (e.g., brake lights) is reduced by half when drivers are conversing on a cell phone. Thus, drivers using a cell phone fail to see information in the driving scene because they do not encode it as well as they do when they are not distracted by the cell-phone conversation. In addition, the diversion of attention from the driving environment increases the time it takes for drivers to respond to changes in the driving scene (e.g., lead vehicle braking and red-onset traffic lights). In situations where the driver is required to react with alacrity, the data indicate that drivers using a cell phone will be less able to do so because of the diversion of attention from driving to the phone conversation. The net result is that activities such as conversing on a cell phone increase the likelihood and severity of accidents on the roadway.

...