It’s not every day that someone must decide how much chili sauce to feed an unsuspecting victim, but Yoon’s initial findings—that just five minutes of playing a stereotyped character can guide a person’s behavior—are leading him to pursue more practical applications of virtual reality and gaming. He’s planning virtual realities that let patients with autism or social anxieties interact with avatars in everyday settings, for instance. And he’s curious about how to use virtual realities to boost healthy habits. In 2010, researchers at Stanford showed that watching an avatar of themselves run on a treadmill made people more likely to work out. Yoon wants to see whether that effect can be caused by an even more subtle immersion — controlling a healthy-looking avatar in a game that’s unrelated to exercise

“Today people have the option of living in their everyday reality, or living in all sorts of virtual realities,” Yoon says. Because they are growing more ubiquitous, it has become all the more important, he says, to understand the covert effects of simulated settings.

So what’s happening in the brain when you unintentionally start to act like an assigned character in a virtual reality, or when you wince in pain when your avatar gets poked? That’s what Olaf Blanke is working to understand.

I ask Blanke what the difference is between seeing a character that you identify as another person, and seeing an avatar that you view as your own body. “The temporo-parietal cortex,” Blanke answers. This area of the brain, where the temporal and parietal lobes meet, is thought to integrate all sorts of information from different sources: what we see, hear and feel.

Blanke was a practicing neurologist, working with stroke and epilepsy patients, when he became interested in what it meant to have a physical sense of self. Some of his patients reported out-of-body experiences after their strokes or seizures, and he didn’t have a scientific explanation for what was happening.

“The patients’ experiences were really like biological avatars,” Blanke says. The patients would feel that their body was located a few feet away from their vantage point; they’d see themselves in the third person.

Blanke started studying the brains of these patients, as well as the brains of people immersed in virtual realities that displaced their physical identity. When you look at an avatar that’s meant to be someone other than you, the temporo-parietal cortex stays quiet. But when the avatar starts mimicking your movements, showing your heart rate or speaking your words — all tricking your brain into thinking the avatar is your own body — the temporo-parietal cortex lights up, just as it does when you watch yourself in a mirror. Similarly, Blanke found that patients with out-of-body experiences often had strokes or seizures that affected this area of the brain. “The initial surprise was just how easy it is to trick the brain,” he says.

Olaf Blanke examines patterns of brain activity associated with interacting with an avatar.

As Blanke carried out studies that required healthy volunteers to interact with an avatar of themselves, he started to notice something else uncanny. “The more you embody the avatar, the less you embody your physical body from your brain’s point of view,” he explains. When someone is truly absorbed in a virtual world, living as their avatar, they’re less likely to notice if you poke their real, physical body. Blanke immediately thought of the implications for treating chronic pain.

Since this initial observation, he’s gone on to show that, indeed, he can decrease the amount of pain someone feels by redirecting their attention to a virtual body. In addition to having an avatar imitate someone’s movements, Blanke has found that a trick involving physical touch really convinces the brain that an avatar is one’s own body. So Blanke’s setup involves simultaneously stroking a person’s back with a stick, and showing their avatar’s back being touched in exactly the same way (it’s a high-tech version of the classic rubber hand illusion).

Now, Blanke is testing the technique in spinal cord injury patients and amputees who have phantom limb pain. By first stroking an amputee’s back, followed by the avatar’s back, and then showing the subject the avatar’s leg being touched in a virtual setting, Blanke hopes he can induce feelings other than pain in their limbs. “We’re working on different cases now where patients could use this technology for acute flare-ups of pain,” Blanke says.

The plummeting price of VR technologies is spurring more clinical studies using virtual environments, Blanke points out. But what that means for consumers isn’t clear — his studies require extra sensors to exactly match up an avatar’s motions with one’s own. “The tracking needs to be ultrafast and robust,” he says. “If you use a VR that’s not perfectly fine-tuned, you get motion-sick.” Though commercial VR devices like the Oculus Rift completely surround your vision with a virtual reality, and track the motions of your head to align what you see, they don’t allow you to, say, see your own hands and coordinate your real-life hand motion with those on-screen hands (at least not yet— companies like Sixense are working on it).

Where avatar-based virtual realities are already being put to use is in psychiatric clinics that specialize in the treatment of phobias and anxieties. They use virtual realities to expose people to their fears in a safe manner. Scared of flying? Spend increasing amounts of time on a virtual plane to teach your brain to stay calm in the air.

Deathly afraid of spiders? A virtual room with some small creepy-crawlies might slowly help you become less terrified.

At the Virtual Reality Medical Center in San Diego, these kinds of therapies aren’t just theoretical; they’re carried out on patients every day. Executive director Brenda Wiederhold, also a researcher at UC San Diego, says she’s been using the technology on patients since the mid-1990s. Before that, clinicians working to calm phobias could either ask patients to visualize their fear, or use the real thing. Both have drawbacks, as only about 15 percent of the population is any good at imagining, Wiederhold says. But the virtual realities are incredibly effective.

“Our brain really doesn’t know the difference between reality and a virtual reality in a lot of cases,” she says. “If I expose you to a spider in a virtual setting, your limbic system will light up just as if you see a spider in real life.”

And once again, the participant isn’t always aware of the effect, or even what’s real or not. After experiencing a virtual airplane, Wiederhold says, she’s had patients comment that the smell of coffee as the flight attendant came down the aisle really helped immerse them in the scenario. Only there was no smell of coffee.