Ergonomics Society of the Human Factors and Human Factors: The Journal

INTRODUCTIONOver the past 10 years, there has been acceler-ated use of cellular or mobile phones. In the UnitedStates alone, there are an estimated 167 millioncell phone subscribers (Cellular Telecommunica-tions Industry Association, 2004). This increasein usage has been coupled with an acceleration inthe number of studies that have attempted to doc-ument the negative safety implications of their usewhile driving (e.g., Alm & Nilsson, 1994; Mc-Knight & McKnight, 1993; Strayer & Johnston,2001). Such studies have been carried out with avariety of methodologies: epidemiological (e.g.,Redelmeier & Tibshirani,1997; Young, 2001), sim-ulatorbased (e.g., Strayer, Drews, & Johnston,2003), and those conducted in basic laboratorysettings, emphasizing low-Þdelity simulations ofthe driverOs information-processing demands (e.g.,Strayer & Johnston, 2001). Finally, some legisla-tive efforts aimed at banning or restricting the useof cell phones have been seen, based in part uponthe research just cited.At present, the impact of cell phone use on driv-ing performance is complicated by conflictingÞndings. For example, Brookhuis, de Vries, and deWaard (1991) showed that in some conditionsdrivers exhibited decreasedlane deviations whileengaged in a cell phone task, whereas others haveshown the opposite effect for tracking perfor-mance(e.g., Strayer & Johnston, 2001). Similarly,numerous studies have shown that people exhibitincreases in response time on a variety of percep-tual and cognitive tasks while they are engagedin