According to a survey released this week, one out of every five teen girls has sent her sexually revealing photos via cell phone or e-mail, or posted her nude or partially nude images online. Though 71 percent of teen girls and 67 percent of teen guys who have sent these photos say they have sent them to a boyfriend or girlfriend, 15 percent overall said they sent nude photos to people they only “knew” online.

A 20-page report on “Sex and Tech” (PDF) survey was released on Wednesday jointly by the National Campaign to Prevent Teen and Unplanned Pregnancy and CosmoGirl.com. In all, 1,280 teens and young adults, ages 13 to 26, were surveyed from September 25 through October 3.

While two-thirds of teen girls who sent or posted sexually suggestive content said they did it to be fun or flirtatious, fifty-two percent did so to give a sexy present to their boyfriends, and 40% said they did it as a joke.

The survey found that the pictures get around. Nearly one-fourth of teen boys said they have seen nude or partially nude photos because someone shared an image that the sender meant to keep private. More than one-third of teens said that exchanging sexy content makes dating or hooking up more likely.

In a statement, Susan Schulz, special projects editor for Hearst Magazines, said: “Teenagers are early adopters of technology. While this tech savvy can be seen as a positive, our study reveals there’s also a negative side. Teenagers should be aware of the real consequences to this type of behavior and we need to provide them with guidance and encourage them to make smart choices.”