By day, Freeman Williams manages a small dental practice in suburban Houston. But on any given night, he's prowling crime-ridden streets and battling ne'er-do-wells in the video game "City of Heroes" as his virtual alter-ego: a female superhero named Robotrixie.

"I get in character voice-wise as much as my male voice will allow," explains Williams, 48, who talks with other players through the game's voice chat feature. "This has become my catharsis, my escape from the work world."

While the idea of gender-bending is hardly new, the vast online worlds in video games such as "City of Heroes" and "World of Warcraft" have become the latest ways for people to forget about their real life and transform into someone — or even something — else.

These are role-playing games after all.

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For many, half the fun can be in the initial character creation process, where you decide the basic look and functions of your digital persona.

Among the crucial questions that need to be addressed: Do I want to heal or dish out damage? Do I prefer green-skinned orcs or pointy-eared elves? And of course, do I want to be male or female?

For a variety of reasons, Williams isn't the only guy with a preference for female characters, according to Kathryn Wright, a psychologist in Raleigh, N.C., who consults for the Web site WomenGamers.com.

In an informal survey she conducted with 64 males, more than half said choosing a female character gave them a distinct gameplay advantage. And while a quarter said they played women characters because it added to the role-playing experience, Wright said others had a simpler explanation: visual stimulation.

"They'd rather look at a character that looks like Lara Croft than a character that looks like Rambo," she said.

But the ensuing gender-bending can result in some unpredictable online behavior.

Williams admits his female choice has caused a bit of confusion among online fantasy pals — some of whom have developed into real-world acquaintances.

"One of the people that I met online who is a mom in Indiana was really intrigued by the fact that I was actually a guy and at the time I was playing a female character," he said. "I had to break the news to her that I'm actually a big hairy guy."

Erica Poole, a 31-year-old legal secretary in Austin, says she's picked up a few ways to spot a male disguised as a female in online games.

"The fact that they are scantily clad is a huge clue," she said. "And often the bigger the breasts, the more likely it's a guy."

Then there are the conversational cues picked up as players type messages to and fro.

"You can ask leading questions that get them to give it away," Poole said. "Also, most guys don't use a lot of emotions, even when they're trying to be a girl, so this can tip off a 'real' girl."

About 38 percent of gaming consumers in the United States are female, according to the Entertainment Software Association.

In an industry where few video games beyond "Tomb Raider" let you be the heroine, never-ending online games give players the power to craft lead characters as they see fit.

That's one of the reasons Poole said she prefers sticking with her gender.

"It's not something I necessarily decided on a conscious level," she said. "One issue is that I don't have the opportunity to play a strong female character in other games. It's a nice change."

For gal gamers, it's all about options and the ability to customize, says Mia Consalvo, an associate professor of telecommunications at Ohio University. Guys, meanwhile, often have more obvious explanations for their digital likenesses, or avatars.

"For the majority of women who play online games, at the very least they want the choice of being able to play female avatars," she said. "The guys want to look at an attractive character, and some of them swear that they get free stuff. Some players just like to experiment with all the different permutations and options in the game."

For some, however, it's more important to stay true to reality.

Mike Janney of Seattle, a software tester for Microsoft Corp. (MSFT), said he always plays a male character: doing otherwise would be disingenuous, he believes.

"I don't tend to role play so much as I tend to just be myself when I'm talking to other players, so I kind of feel like portraying somebody I'm not is not really a good thing," he said. "It's jarring enough to me when I see a male player in a female costume."

Forty-year-old gamer Laurie Stier of Somerset, N.J., says role playing and gender-bending is nothing new — actors and authors have been doing it for centuries, and video games are just the latest way to play a role.

"I mean, how many times has Peter Pan been played as a woman?" she asked. "With role-playing, we are both the writer and the action."