Although there have been many studies on the impact of cell phone use on driving, results often have been contradictory. This study reports on a meta-analysis that was conducted to assess the performance costs associated with cell phone use while driving. A total of 23 studies (contributing 47 analysis entries) met the appropriate conditions for the meta-analysis. The statistical results from each of these studies were converted into effect sizes and combined in the meta-analysis. Standardized measures of effect size along five dimensions were used. Results show clear costs to driving performance when drivers were engaged in cell phone conversations. However, subsequent analyses indicated that these costs were borne primarily by reaction time tasks, with far smaller costs associated with tracking (lane-keeping) performance. Hands-free and handheld telephones revealed similar patterns of results for both measures of performance. Conversation tasks tended to show greater costs than did information-processing tasks. There was a similar pattern of results for passenger and remote (cell phone) conversations. There were also some small differences between simulator and field studies, although both exhibited costs in performance for cell phone use. The overall meta-analysis findings suggest that there are significant costs to driver reactions to external hazards or events associated with cell phone use, and that hands-free cell phones do not eliminate or substantially reduce these costs. The meta-analysis also suggests that some research methodologies or performance measures may underestimate the costs.
Abstract