I figured that one of the best ways to understand the human ability to see in 3D might be to research people who did not have that ability and gained it later in life. Initially, I read that after the age of 3 it was impossible for 3D vision to be acquired. Then I came across the book Fixing My Gaze by Susan R. Barry (aka Stereo Sue). She is a neurobiology professor at Mount Holyoke College. She developed crossed eyes in early infancy, and despite three childhood surgeries, remained cross-eyed and stereoblind. At age 48, she underwent optometric vision therapy and achieved what she and many other scientists and doctors thought impossible: she developed stereovision. Sue has described her vision story and the science behind it in her book Fixing My Gaze.
I found the book absolutely fascinating and I was compelled to reach out to her and ask if she would be able to discuss some important 3D issues with me. She immediately responded by email and what follows is one of our back and forth emails regarding my recent IMAX 3D viewing of James Cameron’s AVATAR.
Almont Green Wrote In An Email To Susan Barry:
A few hours ago I saw Avatar 3D IMAX in Framingham. Also I have been reading threads from
http://mtbs3d.com postings. There are very serious things going on with regards to human perception experimentation on a very large scale and growing exponentially with every passing second.
My experience watching the IMAX movie Avatar felt like I was experiencing mind altering drugs. It was hard to maintain accurate eye tracking – for many scenes my eyes had to diverge so much I felt like Marty Feldman. But it was much more than just experiencing eye discomfort. Standard cinematography technique was no longer familiar. Jump cuts were very startling and created confusion. Camera shake was very unsettling as the motion seen by my eyes did not match what my body was experiencing. Camera pans also created perception confusion as my body did not experience what I was seeing.
Shifts in size and distance – which could never be experienced in real life – had a mind bending extra reality sensation that I can’t describe.
This experience, though startling and somewhat discomforting, was thoroughly compelling and eerily moved from being referential imagery as normal movies are to being perceived as reality and generating a unique emotional response I have never experienced watching a movie.
After the movie, I experienced slight stomach upset and noticed that things looked eerily more sharply defined at the edges. It is as if my eyes were seeing in a subtle new way which lasted for about 30 minutes or so. I don’t experience the sensation now. Things look as they always have.
It was a positive experience that I would like to have again, but I’m not so sure it is a good thing? Now reading about video games coming out in 3D and being seriously promoted makes me wonder about hours and hours spent watching altered perception/reality. Especially, since the experience provides a type of addictive response. I’m not a scientist, but this sure seems like human experimentation on a massive scale with no oversight or concern as to the consequences.
Mr. Cameron spent millions of dollars producing what he felt was a state of the art 3D motion picture. And it had serious flaws in my opinion. I can only imagine low budget games with maybe even reversed eye perspectives or worse!
I think 3D is fantastic, but I have to say that I’m more than just a little concerned.
Susan Barry Wrote In An Email To Almont Green:
Your email was fascinating because many of the experiences you described while watching Avatar were similar to the experiences I had while developing stereovision ie size and distance changes, an increased sense of borders around everything, and an emotional and addictive response. When I first began to see in 3D, the amount of joy I felt was overwhelming, a combination of deep satisfaction and childlike glee. I thought I was completely over-the-top until I talked with other adults who had also acquired stereopsis in midlife and could not describe the experience without tearing up.
Borders and edges look much sharper to me now than before my vision therapy, and this is not a result of acuity changes. My acuity was always correctable to 20/20. An enhanced sense of stereo depth provides an enhanced sense of borders. Shortly after the movie, your stereo system may have been temporarily tuned up. I see this same sort of effect after practicing vision therapy each day. There’s a small but noticeable difference in the sharpness of things, as if everything is more high passed filtered.
When, during vision therapy, I look with polarizing glasses at a polarizing vectogram, the virtual image floats in space. As it recedes, it appears larger and, as it comes closer, it appears smaller. These size changes are due to a phenomenon called size constancy which I explain in chapter 7 of my book. Perhaps, you were getting some of this effect when images floated forward or receded while watching Avatar.
I did not have too much trouble learning to move in an increasingly 3D world because my stereovision came on slowly. But others, for whom stereopsis came on suddenly and in full measure, did feel a disconnect between their movements and their vision and it took a month of re-calibration before they were comfortable.
I loved Avatar, especially the scenes of the jungle receding a great distance at many levels of depth behind the movie screen. (Prior to gaining stereovision, there was never this sense of continuous depth. Instead there was the plane I was looking at and then a vague background.) I was tired by the end of the movie, but all movies tire me out. I saw Avatar on a regular screen, not an IMAX. Scenes receding far into space would have demanded huge divergence movements if I saw them on IMAX, and I wonder if I would have noticed this effort. I practice divergence and convergence movements every day and have built up large fusion ranges and endurance. People really vary in their ability to sustain fusion at different disparities and most people, I would think, would find IMAX 3D viewing pretty exhausting.
When I gained stereovision, I experienced a spatial connection to everything around me. In the past, I could infer distance and depth from monocular cues (perspective, shadows, object occlusion etc.) but this was very different from feeling myself in a volume of space with these solid, space-filling objects all around me. While practicing vision therapy procedures, I recognize when my sense of spatial relations is changing because I feel it viscerally – as sweating, perhaps a bit of nausea, trembling of the right hand. These effects can be subtle but I welcome them now. I would not be in the least surprised if people felt these same sort of feelings while or after viewing Avatar.
There are also issues with accommodation and vergence. As we focus our eyes for near viewing (accommodation) there is a coupled turning in of the eyes (convergence). This relationship is altered in bad 3D movies. Too many scenes of objects coming right toward you put a lot of stress on the visual system. So I think your concerns are very valid especially when 3D is applied to addictive and tension-filled video games. Some 3D movie makers may be very aware of these issues. Did you see UP? It was lovely, and the 3D was produced in a careful and gentle way.
Do you know about the Stereoscopic Displays and Applications conference ( http://www.stereoscopic.org/2010/program.html )? I went to it two years ago, and the people at that conference discussed many of these issues.
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Almont Green comments: I highly recommend the book Fixing My Gaze. Information is available at:
With her unique perspective, I hope to have many more discussions and soon will show her samples of my autostereoscopic life size high dynamic range 3D photographs. It should be quite insightful to witness her reactions.