Behavioral studies have shown that engaging in a secondary task, such as talking on a cellular telephone, disrupts driving performance. This study used functional magnetic resonance imaging (fMRI) to investigate the impact of concurrent auditory language comprehension on the brain activity associated with a simulated driving task. Participants steered a vehicle along a curving virtual road, either undisturbed or while listening to spoken sentences that they judged as true or false. The dual-task condition produced a significant deterioration in driving accuracy caused by the processing of the auditory sentences. At the same time, the parietal lobe activation associated with spatial processing in the undisturbed driving task decreased by 37% when participants concurrently listened to sentences. The findings show that language comprehension performed concurrently with driving draws mental resources away from the driving and produces deterioration in driving performance, even when it does not require holding or dialing a phone. IntroductionAn enduring question about the human mind concerns the ability to do two things at the same time. As technological and informational capabilities of our environment increase, the number of available information streams increases, and hence the opportunities for complex multitasking increase. In particular, multitasking of driving and conversing on a cell phone is technologically available, but intuitively seems dangerous in some circumstances. Although driving becomes sufficiently cognitively automated (Schneider, 1999) to permit experienced drivers to perform other tasks at the same time, such as carrying on a conversation, a large number of behavioral studies have now shown that performing another cognitive task while driving an actual or virtual car substantially degrades driving performance Nilsson, 1994, 1995;Anttila and Luoma, 2005;Beede and Kass, 2006;Brookhuis et al., 1991;Consiglio et al., 2003;Drory, 1985;Engström et al., 2005;Haigney et al., 2000;Hancock et al., 2003;Horberry et al., 2006;Horrey and Wickens, 2004;Hunton and Rose, 2005;Jamson and Merat, 2005;Kubose et al., 2006;Lamble et al., 1999;Lesch and Hancock, 2004;Liu and Lee, 2005;Matthews et al., 2003;McKnight and McKnight, 1993;Patten et al., 2004;Ranney et al., 2005; Nunes, 2000, 2003;Santos et al., 2005;Shinar et al., 2005; Drews, 2004, 2007;Strayer et al., 2003Strayer et al., , 2006Strayer and Johnston, 2001; Bolling, 2005, 2006;Treffner and Barrett, 2004). Although some of these studies show that some aspects of driving are unaffected by a secondary task (e.g., Haigney et al., 2000) and in some cases certain aspects improve (e.g., Brookhuis et al., 1991;Engström et al., 2005), a recent meta-analysis of the literature suggests a large overall decrement in driving performance when a secondary task is added (Horey and Wickens, 2006).