Participants’ performance in the reaction time task corresponded to the temporal interval between the onset of anauditory stimulus and the verbal response. In the arithmetic task, because the duration of each stimulus was variable, theresponse time was defined as the temporal interval between the voice offset and the verbal response onset. When computingthe mean response time (ms) for each dual-task driving session and the baseline condition session, we followed a proceduresimilar to Cantin et al. (2009). This consisted in removing the outlier data for each participant. Outliers corresponded toresponse times faster than 150 ms or slower than each participant’s mean response time plus two standard deviations.The number of errors in the mental arithmetic task was also calculated.