Wherefore, litterbug?

Kaplan is a Times staff writer.

In a series of real-world experiments, people exposed to graffiti, litter and other cues of lawlessness were more likely to commit small crimes, according to a study published today that bolsters the controversial “broken windows” theory of policing.

The idea is that low-level offenses like vandalism and panhandling create an environment that breeds bigger crimes. According to the theory, authorities can help head off serious violence by keeping minor infractions in check.

Dutch researchers tested the psychological underpinnings of the theory and found that signs of social disorder damped people’s impulse to act for the good of the community, allowing selfish and greedy instincts to take over. The results appear in the journal Science.

Community policing strategies based on the “broken windows” theory have taken root in cities across the U.S. and around the world since it was proposed in 1982.


Most famously, New York City saw a 50% reduction in crime in the 1990s after then-Mayor Rudolph W. Giuliani and then-Police Commissioner William J. Bratton -- now head of the Los Angeles Police Department -- cracked down on squeegee-wielding panhandlers and the like. They credited the “broken windows” approach for their success.

An array of social scientists examined the city’s crime statistics, and many of them concluded that factors like the booming economy and decline of crack cocaine were actually responsible for the dramatic improvement.

Kees Keizer, a graduate student at the University of Groningen in the Netherlands, thought psychology and sociology could add to the debate. Human behavior is influenced by three competing instincts: to act in a socially appropriate manner, to do what feels good in the moment and to maximize one’s resources. Keizer predicted that when there’s less motivation to be socially appropriate, the other two impulses would take over.

To test this, he attached fliers for a fake sportswear store to the handlebars of bicycles parked in a shopping area. With no trash can nearby, shoppers returning to their bikes could either take the fliers with them or litter.

A wall near the bicycles had a sign indicating that graffiti was forbidden. When the wall was indeed graffiti-free, 33% of people left the fliers on the ground or attached them to other bikes. After Keizer painted graffiti on the wall, the percentage of litterers rose to 69%.

Keizer said littering jumped because the socially appropriate instinct -- to deposit the flier in a trash can -- was overtaken by the feel-good instinct to let someone else throw it away.

In other experiments, the presence of four shopping carts strewn about a parking lot in violation of posted signs boosted the percentage of people who littered to 58%, from 30%. The sound of illegal fireworks increased the percentage of litterbugs near a busy train station to 80%, from 52%.

To see whether social disorder would induce citizens to steal, Keizer left an envelope containing 5 euros (about $6.26) hanging conspicuously from a mailbox. When the mailbox was clean, 13% of passersby stole the envelope. When the mailbox was surrounded by trash, the percentage jumped to 25%, and when the mailbox was covered in graffiti, it rose to 27%.


“It is quite shocking that the mere presence of litter resulted in a doubling of the number of people stealing,” Keizer said.

James Q. Wilson, the political scientist who developed the “broken windows” theory with George L. Kelling, said the Netherlands experiments bolstered his hypothesis.

“If public authorities worry about order, it affects the way people behave,” said Wilson, now the Ronald Reagan Professor of Public Policy at Pepperdine University in Malibu.

But Bernard Harcourt, a professor of law and criminology at the University of Chicago who has done studies debunking “broken windows,” said Keizer’s scenarios were too quaint to take seriously.


“We don’t care about those kinds of trivial, manipulated delinquent acts,” he said. “What we care about is violence.”