Catherine Devine had her first brush with an online bully in seventh grade, before she’d even ventured onto the Internet.

Someone set up the screen name “devinegirl” and, posing as Catherine, sent her classmates instant messages full of trashy talk and lies.

“They were making things up about me, and I was the most innocent 12-year-old ever,” Devine remembers. “I hadn’t even kissed anybody yet.”

As she grew up, Devine, now 22, learned to thrive in the electronic village. But like other young people, she occasionally stumbled into one of its dark alleys.

A new Associated Press-MTV poll of youth in their teens and early 20s finds that most of them — 56 percent — have been the target of some type of online taunting, harassment or bullying, a slight increase over just two years ago. A third say they’ve been involved in “sexting,” the sharing of naked photos or videos of sexual activity. Among those in a relationship, four out of 10 say their partners have used computers or cellphones to abuse or control them.

Three-fourths of the young people said they consider these darker aspects of the online world, sometimes broadly called “digital abuse,” a serious problem.

They’re not the only ones.

President Barack Obama brought students, parents and experts together at the White House in March to try to confront “cyberbullying.” The Education Department sponsors an annual conference to help schools deal with it. Teen suicides linked to vicious online bullying have caused increasing worry in communities across the country.

Conduct that rises to the point of bullying is hard to define, but the AP-MTV poll of youth ages 14 to 24 showed plenty of rotten behavior online and a perception that it’s increasing. The share of young people who frequently see people being mean to each other on social networking sites jumped to 55 percent, from 45 percent in 2009.

That may be partly because young people are spending more time than ever communicating electronically: seven in 10 had logged into a social networking site in the previous week, and eight in 10 had texted a friend.

Devine, who lives on New York’s Long Island, experienced her share of online drama in high school and college: A friend passed around highly personal entries from Devine’s private electronic journal when she was 15. She left her Facebook account open on a University of Scranton library computer, and a prankster posted that she was pregnant (she wasn’t). Most upsetting, when she was 18, Devine succumbed to a boyfriend’s pressure to send a revealing photo of herself, and when they broke up, he briefly raised the threat of embarrassing her with it.

“I didn’t realize the power he could have over me from that,” Devine said. “I thought he’d just see it once and then delete it, like I had deleted it.”

The Internet didn’t create the turmoil of the teen years and young adulthood — romantic breakups, bitter fights among best friends, jealous rivalries, teasing and bullying. But it does amplify it.

“It’s worse online because everybody sees it,” said Tiffany Lyons, 24, of Layton, Utah. “And once anything gets online you can’t get rid of it.”

Plus, 75 percent of youth think people do or say things online that they wouldn’t do or say face to face.

The most common complaints were people spreading false rumors on Internet pages or by text message, or being downright mean online; more than one- fifth of young people said each of those things had happened to them. Twenty percent saw someone take their electronic messages and share them without permission, and 16 percent said someone posted embarrassing pictures or video of them without their permission.

Some of these are one-time incidents; others cross into repeated harassment or bullying.

Sameer Hinduja, a cyberbullying researcher, said numerous recent studies taken together suggest a cyberbullying victimization rate of 20 to 25 percent for middle and high school students. Many of these same victims also suffer from in-person abuse. Likewise, many online aggressors are also real-world bullies.

“We are seeing offenders who are just jerks to people online and offline,” said Hinduja, an associate professor of criminal justice at Florida Atlantic University and co-director of the Cyberbullying Research Center.

And computers and cellphones increase the reach of old-fashioned bullying.

“When I was bullied in middle school, I could go home and slam my door and forget about it for a while,” said Hinduja. “These kids can be accessed around the clock through technology. There’s really no escape.”