The avatars were rated on a scale ranging from provocative to conservative based on such factors as bust and hip size ("very large" to "very small"), clothing and number of visible navel piercings.
Overall, 40 percent of teen girls followed in the study reported having been approached sexually online, while 26 percent said they had actually met a person they had first encountered online.
Participants who had been abused were more likely to fall into both categories, as were girls with provocative avatars.
"It's not only the perceiver whose behavior we have to be careful about, but also the presenter," Noll said. "Their behavior can change because they see themselves a little bit differently than they really are developmentally. The danger is not only who's out there looking for girls, but how it can change the behavior of the actual presenter."
Unfortunately, these findings likely also apply to Internet sites that rely not on avatars but on actual photographs and written descriptions.
"Kids have put some very provocative stuff on Facebook and other sites, and that's gotten some into trouble," said Alan Hilfer, director of psychology at Maimonides Medical Center in New York City.
Not only predators can see a provocative photo. So can parents. Hilfer recounted the story of a 16-year-old boy who posted a picture of himself with a bottle of beer, which then circled back to his parents.
"Kids are very indiscreet. If it's out there, it's accessible by almost anyone," he said. "I don't think this article is saying anything that most of us aren't aware of but it is certainly something that we need to constantly be monitoring, just like we monitor teenage drinking or substance abuse."
Lack of parental presence is one of the biggest risk factors for inappropriate Internet communication, Noll said.
She advised parents to look at their kids' Facebook site periodically t
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