A study out of the University of Groningen, Netherlands published in the Nov. 20th edition of the journal Science examines the Broken Window Theory of urban order.
The theory was made famous in the 80's when New York City used it to clean up their city by ensuring that the little crimes - from jaywalking to graffiti to breaking a window - were acted upon.
It relies on a couple of assumptions. First, that most people are 'monkey see, monkey do' when it comes to minor crimes - clamp down on the originators and you cut out the number of copy cats. Another is that people's perception of crime is more important than the actual rate of crime in an area - broken glass and graffiti make people feel unsafe.
'Broken Window' has critics who usually claim that the effect is unsustainable in the longer term.
In The Spreading of Disorder the Dutch researchers conclude that: "... when people observe that others violated a certain social norm or legitimate rule, they are more likely to violate even other norms or rules, which causes disorder to spread."
Unfortunately, the full article is hidden behind the subscription shield on Science's website but you can read the abstracts and some of the methodology here. There's also a Bloomberg news article here. I also blogged on the 2008 StatsCan study on neighbourhood incivility: perception vs reality here.