Risk Compensation and Human Behavior in Safety Systems

Key Insight

The common assumption that eliminating identified risks automatically enhances safety is challenged by the theory of risk homeostasis, which posits that human beings inherently compensate for reduced risks in one area by taking greater risks in another. This suggests that changes appearing to increase safety may not actually reduce the overall accident rate. Instead, individuals adapt their behavior, utilizing the perceived safety gains to engage in more adventurous or less cautious actions, effectively 'consuming' the risk reduction rather than applying it to achieve a safer outcome.

A notable experiment in Munich demonstrated this: a fleet of taxicabs equipped with anti-lock braking systems (ABS), which significantly improve braking, showed no reduction in accident rates over three years compared to taxis without ABS. Drivers with ABS, however, drove faster, made sharper turns, displayed poorer lane discipline, braked harder, tailgated, and had more near misses. They utilized the enhanced safety provided by ABS to drive more recklessly, maintaining their perceived level of risk. Further examples include pedestrians being killed more frequently in marked crosswalks due to reduced vigilance, and childproof medicine lids ironically increasing fatal child poisonings because adults became less cautious about storage. The opposite effect also occurs; when Sweden switched driving sides in the late 1960s, fatalities dropped 17 percent as drivers became more careful due to unfamiliarity, before slowly returning to previous levels.

This principle applies to NASA's operations. Decision-making within organizations like NASA has been characterized as 'Russian roulette,' where successful launches despite O-ring problems led to a belief that the risk was lower, and standards could be relaxed. Even if O-rings are improved, risk homeostasis suggests that the organization might simply shift risk-taking to other components, of which there are six volumes deemed equally risky. More broadly, society often prioritizes convenience, cost, or speed over maximizing safety benefits from technological advancements. For instance, the lifting of the 55-mile-per-hour speed limit or the use of aircraft safety improvements for flying in worse weather and heavier traffic demonstrates a societal tendency to consume safety advancements rather than use them to achieve the safest possible outcomes, embedding high-tech catastrophe into daily life.