Risk homeostasis

Laurence Gonzales in Deep Survival. Page 112.

He's talking about a theory called "risk homeostasis." The theory says that people accept a given level of risk. While it is different for each person, you tend to keep the risk you're willing to take at about the same level. If you perceive conditions as less risky, you'll take more risk. If conditions seem more risky, you'll take less risk. The theory has been demonstrated again and again. When antilock brakes were introduced, authorities expected the accident rate to go down, but it went up. People perceived that driving was safer with antilock brakes, so they drove more aggressively. With the introduction of radar in commercial shipping, it was expected that ships would collide less frequently. The opposite proved to be true. Radar simply allowed the owners to require the captains to drive the ships harder. Technological advances intended to improve safety may have the opposite effect.