Bakersfield attacks its ever-present litter challenge Saturday, when scores of teams fan out across the city for the 10th annual Great American Cleanup.

Organizers expect 7,000 or more volunteers to participate in the event, which will send people into neighborhoods and onto roadside right-of-ways to pick up litter, paint over graffiti, and plant flowers, shrubs and trees.

A cynic might suggest that the communitywide litter-fighting effort is futile, because the trash will just return to those parking lots and alleyways in the days, weeks and months that follow. Much of it will, no question -- but credible social-science research demonstrates that these events really do produce meaningful results, and not just in terms of litter eradication.

Researchers from the Netherlands report compelling evidence that the presence or absence of litter and graffiti can have an effect on the way people behave -- and the findings have public safety repercussions. Kees Keizer and his fellow scientists at the University of Groningen created scenarios designed to test whether unappealing conditions could affect people's conduct. Turns out trashy environments doubled the number of passers-by who were prepared to litter and even steal.

In one test, for example, researchers studied an alley that is frequently used to park bicycles. They created two sets of conditions: one of order and the other of disorder. In one, the walls of the alley were freshly painted; in the other, they were crudely tagged with graffiti. The researchers then attached phony promotional fliers to each bike's handlebars. In the graffiti-marred alley, bicycle owners tossed the fliers onto the ground (or stuck them on other bicycles) 69 percent of the time; in the tidy alley, the rate was less than half that.

That and other experiments by Keizer's group seem to validate the "broken window theory" of Rutgers University professor George Kelling, a former probation officer. In the late 1980s, Kelling and a colleague may have been the first to suggest that a few broken windows in an empty building can quickly lead to more smashed panes, more vandalism and, eventually, to break-ins. The likelihood that people will behave in a particular way, the theory goes, can be strengthened or weakened depending on what they observe others to be doing.

In the early 1990s, Felton Earls of the Harvard School of Public Health developed research that in many ways contradicted the "broken window theory" -- but substantiated the power of one common response to certain anti-social behaviors: broad cooperation.

Earls and his colleagues argued that the best answer to negative influences in a given neighborhood, up to and including crime, is neighbors' willingness to cooperate for one another's benefit. Local governments, Earls said, should support the development of cooperative efforts by encouraging neighbors to meet and work together.

And that, of course, is what the Great American Cleanup is all about -- Bakersfield-area residents coming together for a cause that's important to them, creating an environment that dissuades bad behavior.

Want to help? It's not too late, even if you haven't signed up. Just show up at 7:45 a.m. Saturday at Yokuts Park, at the Empire Drive entrance, and organizers will find something for you to do.