LONDON (Reuters Life!) - Graffiti and litter made people twice as likely to steal in a study researchers said on Thursday shows how evidence of social disobedience spurred a surprising number of others to break rules.
The findings reinforce the so-called "Broken Windows Theory" that forms the backbone of crime prevention in many major cities across the world in which police crack down on minor crimes in the belief this will prevent bigger ones, the researchers said.
"We expected the effect but we were surprised by the size of the effect," Kees Keizer, a social psychologist at the University of Groningen in the Netherlands, who led the study, said in a telephone interview.
"If graffiti or litter can induce twice as many people to steal, that is stunning."
In a series of experiments in different city neighborhoods with little crime, the researchers tested whether or not people were more willing to defy social rules when they saw evidence others already had.
They found that about 25 percent of the people observed stole an envelope with a 5 euro note from a mailbox when there was graffiti on nearby walls or litter in the area. This compared to about 13 percent when the walls or areas were clean.
The other experiments showed people were more likely to trespass if they observed that others had illegally parked their bicycle and were more likely to litter if they heard fireworks or saw abandoned shopping carts.
The study is evidence that signs of disorder and petty criminal behavior -- such as broken windows -- can cause disorder to spread and lead to the decay of neighborhoods, the researchers added.
"We found that observing that others violated certain social norms or legitimate rules makes it likely that people also violate other norms or rules, which causes disorder to spread," Keizer and colleagues wrote in the journal Science.
Reporting by Michael Kahn; Editing by Will Dunham and Paul Casciato