A study was published in the Economist stating that people modify their behavior based on what they observe in their environment. Specifically, observing rule breaking increases the likelihood that the observers will also break the rules. The study tested this in multiple ways - one test left an envelope with clearly visible money sticking out of a post box. The number of people who stole it doubled based on whether there was trash and graffiti around the box.

Gus Mueller asked the question - does this apply to code as well as to real environments? My feeling is that it does - but partially. If you establish standards but never apply them, then nobody will follow them. If you establish standards and the code base adheres to it, then new code will likely also adhere.