My friend Macgregor Duncan draws my attention to a WaPo pieceÂ by Shankar Vedantamon how people undermine government intervention by changing their behaviour.
Trying to fix problems that affect vast numbers of people has an intuitive appeal that politicians and policymakers find irresistible, but several warehouses of research studies show that intuition is often a poor guide to fixing systemic problems. While it seems like common sense to pump money into an economy that is pulling the bedcovers over its head, the problem with most social interventions is that they target not robots and machines but human beings — who regularly respond to interventions in contrarian, paradoxical and unpredictable ways. …
Previous research has shown that people drive faster in vehicles that feel safer, attempt to bike on more dangerous terrain when they wear helmets and pay less attention to infants being bathed when the children are in seats that are said to reduce the risk of drowning.
This is a hard area for policy to cleverly address, but an important one to take into account.
Vedantam also quotes a splendid experiment from psychologist Ian Walker.
Traffic psychologist Ian Walker at the University of Bath in England once conducted a similar experiment that vividly illustrates the problem with well-intentioned interventions that backfire.
Walker rode a bicycle equipped with a distance sensor, video camera and a computer. Over 15-to-20-minute periods, he rode with his helmet on, then with his helmet off. He rode some segments three feet from the curb and others closer to the edge of the road. With each iteration, he changed a single variable. In the interest of being rigorous, he even obtained a shoulder-length wig of curly black hair, so that some passing motorists would think he was a woman.
It is not known whether any drivers turned around for a look after they passed the bicyclist. If they did, they would have been puzzled: “It was slightly embarrassing, because I had a beard at the time,” Walker said. “I spent a couple of days going up and down the road wig on, and a couple of days going up and down the road, wig off.”
Walker was trying to figure out whether his interventions changed the way drivers passed his bike. He came to two conclusions: Cars gave him more leeway when drivers thought he was a woman with curly black hair. And they gave him less leeway — getting dangerously close — when he wore a helmet.