Abstract
Two pioneering studies that examined cell phone billing records of people who had been in automobile crashes estimated that cell phone “use” while driving elevated crash risk by a factor of four relative to driving without cell phone use, a substantial increase. Cell phone “use” in these pioneering studies refers solely to cell phone conversation, because billing records contain no information about the visual-manual aspects of cell phone use. Recent research suggests that these pioneering studies overestimated the relative risk of cell phone conversation by a factor of seven due to two major biases. After adjustment for these biases, cell phone conversation does not increase crash risk beyond that of driving without a cell phone conversation, and may, in fact, reduce crash risk. The main reasons are driver self-regulation and reduced drowsiness, which fully compensate for the slight delays in brake response times caused by cell phone conversation.
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Scope
This article is limited to studies that estimate the relative crash risk of conversation on a cell phone during real-world, non-experimental driving in passenger vehicles.
The scope does not include:
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Heavy vehicles such as tractor-trailers or tankers;
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Visual-manual cell phone tasks (e.g., searching for a phone, 10-digit manual dialing, manual texting), and
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Experimental studies of cell phone conversation.
Experimental studies are not included because they cannot make valid estimates of actual crash risk, which requires real-world driving data. Experimental studies are conducted in a driving simulator, on a road or track closed to other traffic, and on public roadways, while the driver is under experimental control. The experimenter usually manipulates the timing and demands of secondary tasks, in artificial scenarios not freely chosen by the driver. In addition, experimental studies rarely represent driving conditions, demand levels, and environmental conditions that drivers will actually experience during real-world driving. In contrast, during real-world driving, drivers can choose whether, where, when, and how to engage in a secondary task during the primary driving task.
Key Terms in this Chapter
Driver Attention: Attention is three entities, not one as commonly believed. The alerting, executive, and orienting attentional networks in the brain are separate networks that can be affected in opposite ways by cell phone tasks. For example, Talk improves alerting attention, while slightly diminishing orienting attention.
Cell Phone Conversation: Talking/listening on a wireless device.
Cognitive Distraction: “Any epoch of cognitive loading that competes with activities necessary for safe driving” (Foley et al., 2013).
Crash Risk: The probability of crash occurrence.
Driver Distraction: “The diversion of attention away from activities critical for safe driving toward a competing activity, which may result in insufficient or no attention to activities critical for safe driving” (Regan et al., 2011, p. 1776).
Compensation: As used here, a synonym for self-regulation. For example, during a cell phone conversation, drivers tend to compensate for the 200-300 millisecond increase in their brake response time by increasing their headway times to a lead vehicle.
Cognitive Load: The loading of cognitive resources, “which are the alerting, executive, and orienting attentional networks singly or in combination, as well as the memory and representational systems (e.g., working and long-term) from which information may be retrieved and in which it may be held and operated upon” (Foley et al., 2013).
Self-Regulation: A change in tactical driving behavior to compensate for adverse effects on safety from a secondary task.
Talk RR: The relative risk of cell phone conversation while driving.