Risk Compensation - Risk Homeostasis

Risk Homeostasis

Professor Gerald J. S. Wilde, a professor emeritus of psychology at Queen's University, Kingston, Ontario, Canada noted that when Sweden changed from driving on the left to driving on the right in 1967, this was followed by a marked reduction in the traffic fatality rate for 18 months after which the trend returned to its previous values. It was suggested that drivers had responded to increased perceived danger by taking more care, only to revert to previous habits as they became accustomed to the new regime. This hypothesis is elucidated in Wilde's book. The hypothesis of risk homeostasis holds that everyone has his or her own fixed level of acceptable risk. When the level of risk in one part of the individual's life changes, there will be a corresponding rise or fall in risk elsewhere to bring the overall risk back to that individual's equilibrium. Wilde argues that the same is true of larger human systems, e.g. a population of drivers.

For example, in a Munich study, part of a fleet of taxicabs were equipped with anti-lock brakes (ABS), while the remainder had conventional brake systems. In other respects, the two types of cars were identical. The crash rates, studied over 3 years, were a little higher for the cabs with ABS, and Wilde concluded that drivers of ABS-equipped cabs took more risks, assuming that ABS would take care of them; non-ABS drivers were said to drive more carefully since the could not rely on ABS in a dangerous situation. There is much more to this study as shown in following reference: Likewise, it has been found that drivers behave less carefully around bicyclists wearing helmets than around unhelmeted riders.

The idea of risk homeostasis has garnered criticism. Some critics say that risk homeostasis theory is contradicted by car crash fatality rates. These rates have fallen after the introduction of seat belt laws.