Neuroscientists have found cells in the visual cortex, the part of the brain that processes vision, whose sole job is to respond to differences in the position of the images transmitted from each eye to the brain. These cells, called binocular neurons, are thought to be the key to seeing in three dimensions. According to the Nobel Prize-winning research from David Hubel and Torsten Wiesel in the s, the brain may only have a short window of opportunity in which to develop binocular vision, in which both eyes are used together.
These doors close early — at the end of childhood — after which people are locked into a two-dimensional world. So throughout his life he saw the world as a collection of flat panels.
Though stereovision is probably the most immediate, and certainly the most sensitive strategy that the brain has for acquiring information about depth, there are other cues that Bridgeman came to rely on heavily,like shading, perspective and occlusion if you look at a forest while moving your head, the trees that are farthest away will blink in and out of view behind the ones that are closest. Looking out the car window, you might see trees right near the road speeding by, jagged rocks a bit further in the distance moving more slowly, and big mountains way out toward the horizon standing still like set pieces bolted to the ground.
This difference in the apparent motion of objects tells the brain how far away each one is from us. Nor does society require that we see in 3D. So for years, Bridgeman believed that the depth cues from motion parallax, shading, and perspective provided decent substitutes for stereovision.
If you ask people with normal stereovision to close one eye and judge the position of objects along the line of sight, they are terribly imprecise, even if they shake their heads to create motion parallax. Bridgeman was struck by the work. According to McKee, he was missing something. Perhaps depth could feel deeper. The same was true in the case of Stereo Sue. Fast forward several years, though, and it became a different story.
Sue sought therapy after experiencing side effects from her vision problems. Most of it involved training her eyes to converge on a single point, as this is the first, crucial step to forming stereoscopic images. She was driving home from the clinic when she first felt it. Space yawned open and the steering wheel just started to hover out in front of her.
Given the overwhelming evidence for a critical period in visual development, most experts assume that Sue — and Bridgeman, by extension — had at least one moment of binocular vision while young, an experience that primed them for full stereovision later in life by initiating the necessary neuronal growth.
And, in fact, Bridgeman does remember one such experience. It was a gimmick on a cereal box that let you fold pieces of cardboard into a stereoscopic image. A university professor who has struggled with depth perception since birth says his vision has dramatically improved after watching 3D movies.
Bruce Bridgeman, a professor of psychology at the University of California, Santa Cruz, lived with poor depth perception until he watched the Martin Scorsese 3D film Hugo, in February Suddenly he was able to see with an improved sense of depth, and the phenomenon continued when he left the cinema. He said he previously "saw the world as kind of, in theory, three-dimensional, but the experience is more flat," Adding: "I didn't realise that until I began to see in proper stereo.
Scorsese is more modest about his first foray into the format. When the legendary director, whose credits include Taxi Driver, Raging Bull and The Departed, announced that he was making a 3D film, he discovered that everyone around him had advice If it couldn't be done, we'd have seen it on the set, in the monitor.
Scorsese even breaks the unwritten "pointy stick" rule and thrusts objects out of the screen into the audience - a gimmick modern 3D films have sought to avoid. When the muzzle comes towards the audience, it has an attitude.
The depth of the shot emphasises that. It underlines it. In 3D it's better. Chris Parks, of Vision 3D, agrees that rules are there to be broken. Part of the joy of 3D is that it gives you a volume. Keeping that volume within a glass box doesn't seem right. Of course, Scorsese is famous for his bravura camerawork - from the rippling, slow motion boxing scenes in Raging Bull to the breathtaking reverse tracking shot in Goodfellas.
Can other directors harness 3D in the way he has? Chris Parks says that, with the likes of Peter Jackson and Steven Spielberg now working in stereo vision, there is hope for the future. And of the dozens of 3D films set for release next year, the one he is most looking forward to is perhaps the most unlikely - Baz Luhrmann's The Great Gatsby. A head and a neck, with a subtle change of expression - a moment of realisation, a flash of guilt, or even just a held stare - it is incredibly powerful.
I believe that filming people's faces in 3D will help to communicate that. The question remains: Can cinema-goers be tempted back into those oddly uncomfortable glasses, after a rash of poor-quality blockbusters like Clash Of The Titans and Green Lantern - all of which were converted into muddy, pop-up book 3D after filming had finished?
But where a film is released in 3D, it still accounts for more than half of the box office.
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