Mark Bolas, director of the MXR Labs at the Institute of Creative Technologies and associate professor at School of Cinematic Arts at USC, explains that one of the reasons virtual reality is so immersive is its wider field of view. A more traditional 60-degree field of view, say, a computer monitor or a window, makes a user feel like she's viewing a world "through a frame." In other words, a TV screen isn't really externalizing her experience.

But with a 90-degree field of view within a headset, that window disappears and the experience becomes very real, Bolas says.

"It's an instinctual medium, which means that you can make thought go away," he explains. If you hear a sound to your right in the virtual world, for example, you just turn to your right. There is no thinking. "We're actually hitting the brain at a different place, [and] we can really start engaging the parts of the brain that are instinctual, and certainly very primitive."

There are plenty of things we still don't know about the brain, but virtual reality is quickly revealing some surprising discoveries.

Oculus VR has experimented with virtual reality in its offices. Many projects focus on representing multiple people in the same virtual reality space, whether via video game or virtual meeting room. One of these early experiments replaced a regular digital avatar with a cube that contained basic human features. The Oculus headset tracked the wearer's eye movement, replicating the same movement on the cube.

As soon as those cubes started moving like human faces, thanks to eye-tracking, the participants quickly perceived the cubes as those people, says Oculus VR CEO Brendan Iribe. "Your brain just fills in the rest. You can tell yourself logically it's just a cube, but when they move the same ways, your brain is like, 'Yup, that's a human.'"

As we create these simulated humans inside virtual reality — and then trick our brains into thinking they are real — what kinds of experiences will we build in five, 10 or 20 years? And will the people driving those experiences have very specific motives or agendas? Does virtual reality have the power to manipulate?