You’re a smoker.  Or at least you were.  On the strong advice of your doctor, following endless nicotine patches, you’ve succeeded in giving up.  Congratulations!  Your risk of developing any of a host of smoking-related illnesses has just dropped dramatically.  You might also expect your life expectancy to increase.  The news is a little less good there.  In fact, one study showed that those who had given up smoking actually died a little sooner than those who continued.

In flood-ravaged countries in the developing world, when you build a levee you can significantly reduce the risk of flooding.  However, research shows that, despite the success of the levees, the actual number of flood victims remains about the same.


These results can be explained by something the Canadian Psychologist Gerald J.S. Wilde called Risk Homeostasis.  Homeostasis is the process in biology which keeps things about the same.  Think of your body temperature.  You have a normal temperature of 37.0 °C (98.6 °F).  When your core temperature rises, you start sweating and blood flows to the surface of your skin to cool you down.  When your temperature cools below 37.0, you start shivering to generate heat.  Risk homeostasis works like this.  We all have a level of preferred risk.  This varies between people but stays the same for any given person over time.  Fairly obviously, if we are in a situation of higher risk than our preference, we act to reduce the risk.  More surprisingly, if the risk is lower than our preference, we also act; this time to increase our risk.

This was most powerfully demonstrated in a taxi fleet in Munich.  Half the fleet were equipped with ABS (anti-lock braking system).  Half the fleet had conventional brakes.  ABS makes the car safer by reducing skidding under braking.  However, the number of accidents in those using ABS was the same as those using conventional brakes.  Drivers with ABS could recognize their cars were safer, so what did they do?  They responded by driving more dangerously to increase the risk back to their preferred level.

This effect was nicely used by Volvo, who are well known for building a brand around safety.  This was a very successful strategy in the 70s and 80s, but became a less potent proposition into the 90s as all cars got safer.  Volvo asked themselves the question: why do you want to be safe.  The answer they came to is that having a safer car allows you to do more dangerous things.  The resulting adverts showed Volvos driving through volcanoes and ice fields.  This was risk homeostasis in action.

So when a successful drink-driving campaign in British Colombia reduced alcohol-related accidents over a four month period by 18%, it should come as no surprise that accidents that were not alcohol-related increased by 19%.  Or that smokers who quit, simply increased their other non-healthy behaviors.  Or that people living in areas which are less prone to flooding due to levees increasingly build houses on the more fertile, more risky, flood plains.

On a personal note, my wife and I often commented that whenever our lives seemed to be ‘settling down’, we would do something which dramatically de-stabilized everything again.  What we didn’t realize at the time is that we were simply finding our way back to our preferred level of risk.

The lesson from this is to be mindful about your risk-related choices.  Like so many areas of human judgment, these decisions about adjusting risk are not explicit, conscious decisions.  The taxi drivers will not have thought ‘Oh, I’m a little safe in this car…better change that!’  If you want to increase the risk in your life or career, create the capability and motivation first by increasing your sense of safety.  If, on the other hand, your life has just got a lot safer, your attraction to risk-taking behaviors is likely to shoot up.  Be ready for this, and meet that need by choosing risk that is productive (or at least not harmful).


Wilde, Gerald JS (1994) Target Risk: Dealing with the danger of death, disease and damage in everyday decisions. First Edition. Web edition: