TORONTO - For all its obvious benefits, there is also a dark side to the cyberworld: online stalking and harassment that can leave victims feeling as if there's no safe haven providing escape from their pursuers.

"It's a new method for an old problem," says Dr. Elizabeth Carll, a clinical psychologist in Long Island, N.Y. "Obviously the ones that everyone is aware of is putting false and humiliating information on the Internet, such as discussion boards, blogs, message boards, Facebook, as well as sending harassing emails and text messages."

But the psychological fallout from such electronic bully tactics can be even more devastating for those targeted than face-to-face exchanges, said Carll, who presented a talk on the issue Saturday at the annual meeting of the American Psychological Association in Washington

"The symptoms of harassment and e-harassment are very similar — anxiety, fear, nightmares, feelings of helplessness, hypervigilence, having eating and sleeping difficulties, feeling out of control, a loss of personal safety — all of those kind of things go with harassment," she said.

"But what's different is that it is more intense because the electronic harassment is so much more pervasive. Whatever humiliating thing they want to say about you can go out to everybody and they can continue to do this wherever you are, if you're online."

Someone being harassed at work can't necessarily evade their persecutor at home because computers and cellphones can allow incoming emails, texts and phone calls to continue 24-7, she said. Even telephone caller ID isn't foolproof for avoiding contact — there are ways to alter the name that comes up when the phone rings, a technique dubbed "caller ID spoofing."

Cyberstalking is particularly traumatizing because its reach is global, Carll said in an interview from Washington.

"So it's not like only your school knows what's going on, but the whole world does. It's out there online, and you know how hard it is to get something off the Internet — when it's on, it's also staying there forever.

"Whereas in real-world bullying and harassment, once it stops, it stops."

Citing statistics from the U.S. Justice Department and other sources, Carll said 850,000 American adults, mostly women, are targets of cyberstalking each year.

— 40 per cent of women have experienced dating violence delivered electronically, including harassing text messages and disturbing information about them posted on social media sites.

— 20 per cent of online stalkers use social networking to keep tabs on their victims.

— 34 per cent of female college students and 14 per cent of male students have broken into a romantic partner's email.

One insidious form of cyberstalking involves installing spyware on a victim's computer, allowing the perpetrator to read the person's personal emails, track websites visited and steal passwords. "They could also send viruses and spam and harmful programs that could compromise or destroy their computer," she said.

In a highly publicized Canadian case in 2006, an Alberta man was sentenced to a year in jail after being convicted of criminal harassment for using the Internet to turn his ex-girlfriend's life upside-down.

Jonathan Barnes, then 32, used Internet keyloggers — a type of surveillance software — and fake email addresses in his harassment campaign, which included hacking into Cari Benson's cellphone and bank accounts, and sending embarrassing pictures of her to her friends, co-workers and family.

In Canada, cyberstalking can be prosecuted as criminal harassment under Criminal Code section 264(1), which includes a subsection prohibiting: "repeatedly communicating with, either directly or indirectly, the other person or anyone known to them."

A number of American states are looking at legislation to counter cyberstalking, while some already have laws in place.

Last month, two Seattle-area girls, aged 11 and 12, were prosecuted for posting sexually explicit photos and messages on a 12-year-old classmate's Facebook page. They also instant-messaged "random individuals" under the girl's name to arrange sex acts.

The two tweens were charged with first-degree computer trespassing and cyberstalking; the 12-year-old was sentenced to six months of supervised probation with community service, while the 11-year-old was given a diverted sentence, meaning her case will be dismissed if she abides by probation requirements.

An investigation into the online harassment began when the victim's mother called police.

Carll said that if ignoring a cyberstalker's actions doesn't stop the harassment, then getting law enforcement involved may be the only way to bring it to an end.

And those targeted should never respond to the person bedevilling them online, she said. "So you would not engage in going back and forth with them.