WASHINGTON » Young people are having a harder time keeping their profile pages and email accounts secure, especially from prankster friends. And although many treat hacking or spying as a joke, nearly half who have been victims were upset by it.

An Associated Press-MTV poll finds 3 in 10 teens and young adults have had people get into their Facebook, Twitter, MySpace or other Internet accounts and either impersonate or spy on them. That’s nearly double the level seen in 2009.

The poll found solid majorities saying they knew who was behind it: 72 percent for spying, 65 percent for hacking.

Richard Lindenfelzer, 20, says it’s happened to him, but it was more playful than anything else.

Sometimes when he walks away and leaves his laptop logged into Facebook, a roommate seizes the opportunity to fiddle with Lindenfelzer’s page, writing silly things about love interests or potty humor.

"It’s meant to be funny," said Lindenfelzer, a junior at Ithaca College in New York. "It’s supposed to be obvious that this is something I would never say."

The same thing happened to recent college graduate Emily Feldhake of Pickford, Mich.

The 22-year-old had used a friend’s laptop and closed the browser but hadn’t logged out. Her friend took some humorous jabs at her on her Facebook page. Not upset, she said: "I knew who it was. It was my friend and I was the one who stayed logged on."

But sometimes the hacking can be malicious.

Courtney Eisenbraun of Saint Francis, Minn., is among the 46 percent of young people left upset by a hacking experience.

The 15-year-old says she was at practice for her high school dance team when she got a text from her sister checking to see if the 10th-grader was on Facebook. The teen’s status had been changed to say something inappropriate about girls in showers.

She says she doesn’t share her password with friends but assumes it was someone in her grade because they knew who her friends were and also posted things on their Facebook pages, pretending to be her.

"I was really confused about how they got my password," she said. "I felt violated."

Eisenbraun changed her password right away, and changes it often now. She hasn’t had another problem.

In the AP-MTV poll, two-thirds of those who had been hacked said at some point they’ve changed their email, instant messaging or social networking password in response to digital abuse. Forty-six percent have altered their email address, screen name or phone number, and 25 percent have deleted a social networking profile.

Josie Burris, 16, says she’s shared her Facebook password with her best friend as well as her boyfriend. Once, she spied on her boyfriend’s page to peek at his private messages and see what he was up to. He’s also spied on her private messages, she said.

"I don’t care. I’ve done it to him. He’s done it to me," said Burris, a junior in high school who lives in Ridgeland, S.C.

She says her parents are on Facebook, too, but she doesn’t worry about them spying on her.

"I make sure I don’t put anything bad on there," she said, but added: "Old people shouldn’t have Facebook. I firmly believe in that."

Child safety advocates, though, say parents should be on Facebook. They don’t suggest spying, but they do say parents need to know where their kids are going online and, most importantly, they need to talk with their children about being responsible online.

Marsali Hancock at the Internet Keep Safe Coalition says children who grow up thinking they’re sending confidential messages are misled.

"It’s never private," says Hancock, president of the coalition. "So the parents who actually check in, even just randomly every now and then, really help their child to recognize that everything can be viewed and tracked and stored and moved around."

Of the young people who said they had been hacked, the AP-MTV poll found that about 7 in 10 said they had considered that their words or pictures could be shared without permission, compared with just over half of those who had not been hacked.

The Associated Press-MTV poll on digital abuse was conducted online Aug. 18-31 and is based on 1,355 interviews (631 teens ages 14-17 and 724 young adults ages 18-24). It was part of an MTV campaign, "A Thin Line," aiming to stop the spread of digital abuse.

The survey was conducted by Knowledge Networks, which used traditional telephone and mail sampling methods to randomly recruit respondents. People selected who had no Internet access were given it for free. The margin of sampling error for the poll is plus or minus 3.8 percentage points.