The “broken windows” theory of crime is correct:
Kees Keizer and his colleagues at the University of Groningen deliberately created such settings as a part of a series of experiments designed to discover if signs of vandalism, litter and low-level lawbreaking could change the way people behave. They found that they could, by a lot: doubling the number who are prepared to litter and steal.
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His group’s first study was conducted in an alley that is frequently used to park bicycles. As in all of their experiments, the researchers created two conditions: one of order and the other of disorder. In the former, the walls of the alley were freshly painted; in the latter, they were tagged with graffiti (but not elaborately, to avoid the perception that it might be art). In both states a large sign prohibiting graffiti was put up, so that it would not be missed by anyone who came to collect a bicycle. All the bikes then had a flyer promoting a non-existent sports shop attached to their handlebars. This needed to be removed before a bicycle could be ridden.When owners returned, their behaviour was secretly observed. There were no rubbish bins in the alley, so a cyclist had three choices. He could take the flyer with him, hang it on another bicycle (which the researchers counted as littering) or throw it to the floor. When the alley contained graffiti, 69% of the riders littered compared with 33% when the walls were clean.
To remove one possible bias — that litter encourages more litter — the researchers inconspicuously picked up each castaway flyer. Nor, they say, could the effect be explained by litterers assuming that because the spraying of graffiti had not been prevented, it was also unlikely that they would be caught. Littering, Dr Keizer observes, is generally tolerated by the police in Groningen.
The other experiments were carried out in a similar way. In one, a temporary fence was used to close off a short cut to a car park, except for a narrow gap. Two signs were erected, one telling people there was no throughway and the other saying that bicycles must not be left locked to the fence. In the “order” condition (with four bicycles parked nearby, but not locked to the fence) 27% of people were prepared to trespass by stepping through the gap, whereas in the disorder condition (with the four bikes locked to the fence, in violation of the sign) 82% took the short cut.
Nor were the effects limited to visual observation of petty criminal behaviour. It is against the law to let off fireworks in the Netherlands for several weeks before New Year’s Eve. So two weeks before the festival the researchers randomly let off firecrackers near a bicycle shed at a main railway station and watched what happened using their flyer technique. With no fireworks, 48% of people took the flyers with them when they collected their bikes. With fireworks, this fell to 20%.
The most dramatic result, though, was the one that showed a doubling in the number of people who were prepared to steal in a condition of disorder. In this case an envelope with a €5 ($6) note inside (and the note clearly visible through the address window) was left sticking out of a post box. In a condition of order, 13% of those passing took the envelope (instead of leaving it or pushing it into the box). But if the post box was covered in graffiti, 27% did. Even if the post box had no graffiti on it, but the area around it was littered with paper, orange peel, cigarette butts and empty cans, 25% still took the envelope.
The researchers’ conclusion is that one example of disorder, like graffiti or littering, can indeed encourage another, like stealing. Dr Kelling was right. The message for policymakers and police officers is that clearing up graffiti or littering promptly could help fight the spread of crime.