Imagine standing on an empty street corner when you hear the rumble of a bus coming around the corner. The breaks squeal as the vehicle stops in front of you. Its doors open; passengers begin to step off. A moment later, the bus explodes into flames, temporarily blinding you with light, and showering the street with shards of glass and burning shrapnel. The ground shakes. Body parts lie on the pavement around you. You hear screaming and the sound of sirens. And then you take off your headset—safe and sound in your therapist's office.
Survivors of suicide-bomber attacks in Israel are using this virtual-reality simulation as part of their treatment for post-traumatic stress disorder, or PTSD. In case after case, ongoing studies—which began in the 1990s with Vietnam veterans—show that virtual reality holds exciting potential for enhancing the use of "exposure therapy," in which patients are encouraged to actively and repeatedly engage difficult memories, or "hot spots." Although the research is not yet ready for widespread clinical use, the technology is proving to be a valuable tool. By establishing a context for patients to tell their stories and uncover suppressed details, it can help kick-start the therapeutic process.
Israel is a logical place to start. Dr. Tamar Weiss at the University of Haifa was a pioneer of virtual-reality therapy during the second intifada, when buses were common targets for suicide bombers who killed and injured thousands of Israelis and Palestinians. "Some have suggested that our whole country is walking around with subliminal PTSD," says Weiss. After the attacks on the World Trade Center, Dr. JoAnn Difede recognized the need to find effective treatment for survivors with PTSD, and only months later she had a simulation up and running at the Weill Medical College at Cornell University. "It was a pretty serious public-health problem," says Difede. The technique is also being tested in U.S. military medical centers, where many veterans of Iraq and Afghanistan have combat-related mental-health problems. It is especially important in work with soldiers who find therapy embarrassing but are less self-conscious when wearing a virtual-reality headset.
Exposure to simulation is generally meted out gradually. A veteran injured in an ambush or by a roadside bomb may suddenly find himself back at the steering wheel in a military convoy driving through Baghdad. "Sometimes we're finding it's all they can do to just sit in the Humvee," says Dr. Hunter Hoffman of the University of Washington. Cautiously, new elements are introduced. A car swerves into the oncoming lane; someone suddenly darts across the street. The culmination may be a windshield riddled with gunshots, or an explosion from a pile of debris. Survivors of September 11 may spend their first sessions simply looking up at the towers of the World Trade Center. Over time, they work toward watching a plane crash into one of the buildings. The tremor of the explosion and the smoke are slowly added. Eventually the second plane hits, people can be seen jumping from the upper floors and the buildings collapse. While such a brutal reliving of the event may seem to be the antithesis of therapy, it gets patients to confront their "hot spots" so that they're better prepared to handle their emotions when a memory is triggered in the real world.
When it comes to graphics, less is often more. Therapeutic simulations need only be realistic enough to persuade us to play along. The more lifelike a simulation becomes, however, the more we notice its discrepancies with the real thing, says Ari Hollander, who designed the bus-bomb scenario. The goal in therapy is to re-create just enough details so that we engage in the believability, or "presence," of the virtual world, and allow patients to affix their own unique experiences.
The most compelling effects aren't necessarily visual. Researchers found back in the 1990s that very simple elements, such as the noise of a helicopter overhead or the sound of machine-gun fire, were enough to send a veteran several decades back in time. Since then, virtual reality has since been used to treat more benign conditions, such as phobias, or even how to prepare for a job interview. Overcoming a fear of flying is more cost-efficient in the virtual world than on the tarmac.
The biggest advantage of virtual reality is control. If the exposure proves to be too much for the patient, therapists can simply turn off the simulation. Researchers can more easily determine which stimuli elicit certain responses in the virtual world than in the ambiguity of everyday life. When Dr. Daniel Freeman, author of "Paranoia: The 21st-Century Fear," wanted to determine the level of paranoid thinking in the general population, he looked to virtual reality because it's much easier to design a study when you can control exactly which stimuli a subject is exposed to. He developed a simulated ride on the London Underground, a setting already charged by fear of terrorist attacks, and found that a significant number of people responded to normal behavior, such as someone's making brief eye contact on the train, with mistrust.
The virtual world may also one day help ordinary people kick back and relax. VR applications like those that help burn victims take their minds off pain during excruciating medical treatments could provide a respite from demanding jobs, day-to-day stress or economic turmoil. What that might look like is anybody's guess. Virtual cocktail hour, anyone?