An experimental test of risk compensation: between-subject versus within-subject analyses.

This study examined parameters under which risk compensation in driving can occur following the use of safety belts. Risk compensation theories hypothesize that if individuals use safety belts, they will drive in a more risky manner than if they do not use safety belts due to an increased perception of safety. Although the existence of risk compensation in driving has been debated in the literature for many years, the current study was the first experimental analysis of this theory that permitted a controlled examination of both between-subject and within-subject effects. This study required subjects to drive a 5-hp. go-kart around an oval track either buckled or unbuckled in the first of two phases of 15 driving trials. After the first phase the safety condition was switched for half the subjects (i.e., the safety belt was removed from subjects using it or was used by subjects who previously did not use it). Dependent measures included latency for each lap, deviations from the prescribed lane, and perceived safety while driving. The amount of time it took for subjects to travel to the go-kart track and their safety belt use during that trip was also measured. Risk compensation theory was not supported in the between-subject analyses of the research data; however, some within-subject comparisons did demonstrate risk compensation. Subjects who switched from not using the safety belt to using it increased driving speed during the second phase significantly more than subjects who used the safety belt during both driving phases. The study suggested that the occurrence of risk compensation is dependent upon individuals being able to compare the sensations using a safety belt with those of not using a safety belt. Risk compensation did not manifest itself in between-subject studies because this comparison could not take place. The implications of this study to driving automobiles on multi-user roadways is discussed. Suggestions for research to further expand the knowledge about how and when risk compensation occurs are also provided.