Another note from Jeff Speck’s book: risk homeostasis, or risk compensation.
Risk compensation is a theory which suggests that people typically adjust their behavior in response to the perceived level of risk, becoming more careful where they sense greater risk and less careful if they feel more protected. Although usually small in comparison to the fundamental benefits of safety interventions, it may result in a lower net benefit than expected.
This is why advances in safety don’t necessarily make us all safer. More safety means people will take more risks, thus compensating negatively for some of the safety gained by the advance.
The example the book used was childproof medicine – people are apparently less careful with their medicine if it’s perceived (and marketed) as “childproof,” thus negating some of the safety achieved by said childproofing. (I searched for some reference to a study on this, and all I found were lots of references to Malcolm Gladwell’s “What the Dog Saw,” where he apparently discusses it.)
But the Wikipedia page (linked above) has a bunch of examples –
- Condom distribution programs make people riskier with sexual activity
- Skiers wearing helmets go faster than skiers without helmets
- Drivers wearing seatbelts drive faster than drivers without
- Drivers with anti-lock brakes follow other drivers more closely
One of Speck’s main arguments is that wider traffic lanes and streets are counter-intuitively less safe because they simply prompt drivers to go faster.
(He also points to the interesting case of Sweden in 1967, when the country switched from driving on the left to driving on the right. Traffic fatalities dropped 17 percent, only go back to their prior levels three years later. The theory is that this is risk compensationin reverse – driving on the other side of the road freaked everyone out, so they felt less safe, and acted more cautiously because of it. As time wore on, they got used to the change, their fear lessened, and they went back to being as careless as they were before.)
Another example that occurred to me is in American football vs. rugby. Rugby players don’t wear pads, while American football players are completely armored up. Yet, my perception is that injuries are lower in rugby. This might be due to the fact that, without pads, you’re going to take as much damage as you inflict, so players moderate their behavior considerably. Put another way, when you put enough pads on a football player, he thinks he’s invincible, and acts accordingly.