A Clean Epidemic

Is littering contagious? That's the premise behind the Broken Windows Theory, the influential idea, proposed in 1982 by James Q. Wilson and George L. Kelling, that the condition of the environment has a significant effect on whether people commit crimes. Surprisingly few experiments have explored the theory, but a recent Dutch study offers intriguing support.

In one setup, researchers attached fliers to the handles of bicycles parked in an alley; a sign nearby prohibited graffiti. Typically a third of bicycle owners tossed the fliers on the ground. But when graffiti were sprayed on the wall, more than two-thirds of cyclists did so. In another experiment, researchers left cash sticking out of a mailbox. When the surroundings were tidy, 13 percent of passersby took the money; when trash was strewn around, the figure rose to 25 percent.

The results suggest that if people see one law or social norm being broken, they are more likely to violate another. One wonders how far the reverse logic might be extended. Would a national campaign to literally clean up the streets produce other measurable social benefits? There's only one way to find out.