Matsuura, T., National Research Institute of Police Science, Japan
Many studies suggested that a higher accident rate of young-novice drivers is partly due to their overconfidence. This comes from the results that they assessed their driving skill as good as or better than the average driver. However, a higher self-assessment does not necessarily mean overconfidence. In order to measure a driver's overconfidence, it is necessary to examine whether the driver's self-assessed driving skill is higher than driving skill. Thus, this study investigated both driving skill and self-assessed driving skill of drivers (N = 226). Driving skill was measured by an in-car observation, and self-assessed driving skill by a questionnaire with three 5-point rating scales (below average to above average). Overconfidence score was calculated by subtracting T score of driving skill from that of self-assessed driving skill. Regression analyses with overconfidence score as a dependent variable were conducted with years of driving, age, and total kilometrage as an independent one. Drivers just after getting their driver licence showed lower overconfidence scores (i.e. under-confidence). But the scores increased after that until 5 years of driving, and decreased thereafter. Overconfidence scores decreased with age (18-40 years). Contrary to age, overconfidence increased with total kilometrage after licensing. Namely, the rise continued up to 50,000 km. After that overconfidence decreased gently until 150,000 km, and recovered thereafter. Results suggest that young- novice drivers are overconfident compared to other drivers not because of their poor driving experience but because of their youthfulness.