One moment I'm in a room full of people, the next I'm in the sun-scorched Australian Outback. But it takes more than the fancy graphics of the Samsung Gear VR virtual-reality headset I've just lowered over my head to convince me I'm really hanging out with aborigines.
What it takes, says Richard Marks of Sony's VR arm, PlayStation Magic Lab, is something virtual-reality pros call "presence."
"Presence starts with the image being right," Marks says. "We're getting very good at making the images look good. Add in spatialized audio and you become even more convinced that you're present somewhere."
Marks was one of the filmmakers and content creators discussing VR at last month's Sundance Film Festival, which saw an explosion of interest in the topic and many festival-goers trying Gear VR, Oculus Rift and Google Cardboard VR headsets for the first time.
How do you make them want to return for a second, a third and a 50th time?
It's a question of great importance to high-tech companies looking for the next big thing and already banking on virtual reality taking off in 2016. Investments in VR by the likes of Facebook, Google, Samsung and Sony, along with well-funded startups like Jaunt, NextVR and Magic Leap, are expected to change the way we play video games, take field trips, and watch sports and movies.
Jason Rubin, head of Oculus Story Studio, points to demos in which people are asked to step into what looks like a yawning abyss. "I could reach out and grab the hand of somebody I know well," Rubin said, "holding their hand in the real world -- and they won't do it. And you know you have them. That's presence."
Another VR expert, Caecilia Charbonnier, who is working on experimental multiuser VR, outlined her "four pillars" of presence:
Illusion of being in a stable space
That is, being able to see the world around you. Today's headsets and displays have that cracked.
Illusion of self-embodiment
This involves tracking the movements of your body and playing them back within the virtual world so you can see yourself in the virtual space when you have the helmet on. This is in the early stages with, for example, Oculus Touch controllers you hold in your hands.
Illusion of physical interaction
This involves holding physical props in your hands in the real world and seeing them interact with the virtual space. Charbonnier's team has developed a simple stick you hold that looks like something different in the virtual world, such as a torch you can use to light your way.
Illusion of social collaboration
This involves interacting with other headset wearers in the virtual world. It's real cutting-edge stuff, but Charbonnier's team is using motion tracking to let two people interact in the same space. For example, if one person walks off with the torch, the environment goes dark for the other person. They can even throw physical props to each other.
In the video below, two users interact with each other in a demo.
A word in your ear
When it comes to presence, less is often more. "If you can whisper in somebody's ear, that's the most powerful form of presence I've ever had in VR," said Oculus' Rubin. A character is "in my personal space and it evokes a very powerful emotion."
Sound is also important to help you locate yourself in the virtual environment. In this video, the creators of "Collisions," the VR experience I watched, discuss using the Dolby Atmos sound-mixing system to help place you in the Australian Outback.
The fragility of presence
Paul Raphaël of Felix and Paul Studios compares presence with mindfulness, the concept of focusing on the present moment.
"We're rarely actually present in the real world," he said. "One of the beauties of VR is that it takes someone who's never even thought about meditating and almost by default puts them in a meditating state...That's something people train their whole lives to accomplish."
As important as presence is in a successful VR experience, it's also fragile, Raphaël said. "It's like a small bird you can very easily kill."
Mike Woods, formerly of noted special effects company Framestore and later a co-founder of VR company White Rabbit, lays out some of the many difficulties of evoking presence.
"Having humans close to you, talking to you -- we tried every which way to get that right," Woods said. "There are so many things that we don't realize we're perceiving when we're having a conversation with someone. If I'm talking to you, your face and all the muscles in your face change, which is something we inherently understand. It's really hard to get that right."
Conversely, inducing a sense of presence too successfully can create a new set of problems.
"I've done some of those demos with the jump scares or the horror themes that are really terrifying," said YouTube star Matthew Patrick, aka MatPat, who is now creating VR experiences. "It feels like that murderer is coming at you or that ghost is jumping out right in your face. And if you're someone with a bad heart, that poses a very significant threat."
Established forms of media such as movies and video games have faced controversy over whether viewers can distinguish between fiction and reality. With its heightened sense of immersion, that's likely to be an ethical question facing VR too.
"As with any evolving medium, there are ethical considerations that we're going to have to take into account," Patrick said, "whether it's ratings systems or parental guidance or lockouts. That should be a high priority, as these [VR systems] are entering homes this year."
Or as Woods puts it, "There is a part of the brain that knows you have a headset on. Disabling that part of the brain is the really hard part. But do we want to go down the path where we disable that part of the brain?"