There are more expert drivers in the United States than any other type of expert. A 35-year-old Los Angelino who commutes an hour to work and travels only minimally on weekends will have spent over 10,000 hours behind the wheel, a number sometimes held up as a threshold for expertise (Chase & Simon, 1973). If, however, instead of a time-based definition, one takes as the criterion for expertise performing a task better than someone with less experience, then our opening assertion about expert drivers in the United States is less apparent.

In the transportation domain, defining expertise in any absolute sense is nontrivial. Self-evaluations, as is often the case, place most drivers as above average (Waylen, Horswill, Alexander, & McKenna, 2004) and are at best weakly correlated with evalua tions of a driving instructor (Groeger & Grande, 1996). If we searched the literature for “highly experienced” operators back to the turn of the last century, we would find a plethora of transportation studies, but they would not inform modern notions of expertise.

Instead, we chose to look at relative differences in experience. Table 20.1 details the participant characteristics for a number of the studies reviewed here, along with one modern-day classification scheme (Hoffman, 1996). Expertise is usually defined by number of years operating the vehicle, or miles driven, or hours flown by the operator. Table 20.2 shows a variety of comparisons in relative experience.