By Mark Pesce, February 12, 2010
Virtual reality headsets use the same technique for displaying 3D as we find in movies or 3D television sets – parallax. They project a slightly different image to each one of your eyes, and from that difference, your brain creates the illusion of depth. That sounds fine, until you realize just how complicated human depth perception really is. The Wikipedia entry on depth perception (an excellent read) lists ten different cues that your brain uses to figure out exactly how far away something is. Parallax is just one of them. Since the various movie and television display technologies only offer parallax-based depth cues, your brain basically has to ignore several other cues while you’re immersed in the world of Avatar. This is why the 3D of films doesn’t feel quite right. Basically, you’re fighting with your own brain, which is getting a bit confused. It’s got some cues to give it a sense of depth, but it’s missing others. Eventually your brain just starts ignoring the other cues.