A Discussion With Neuroscientist Susan R. Barry, Ph.D.

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.
————————–end of email, signature snipped…

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.




Filed under 3D Photography

7 responses to “A Discussion With Neuroscientist Susan R. Barry, Ph.D.

  1. Yes! Stereo Sue is amazing and extremely approachable, considering she is a “rock star” in the field of vision therapy.

    I must say, from the perspective of someone whose career is to provide stereoscopic vision to patients, your blog and art is fascinating. I didn’t notice if you are on Twitter, but I am certainly adding your feed to my RSS reader.

    Thanks and keep up the good work!


  2. I decided to abandon Twitter and focus on this blog since the information here lends itself to more than a sentence or two.

    Thank you for the kind words. I have had a few additional discussions with Stereo Sue and am thinking about doing some autostereoscopic photographs that might have application for vision therapy and/or evaluation purposes – specifically, noting 3-4 month old baby reactions to 3D faces.

    More on that on a later post.

  3. Bruce

    Our 8 year old son doesn’t have stereo vision due to Strabismis. He has had two surgeries that have only “fixed” his eyes cosmetically. He currently sees 20/20 in both eyes with glasses .

    We live in a small town with only one vision therapist. After 6 months of “treatment” they still seem pretty clueless.

    With all of the advances in 3D technology is there anyone researching any type of video game therapy for stereo blindness?

    Thank you,

    • Given that there are still those in the medical field that say it is unlikely or even impossible for children beyond the age of 1 to acquire stereo vision I’d say that therapy for the purpose of gaining stereovision is not as widespread and sophisticated as it should be. As Susan Barry has so eloquently demonstrated, it is absolutely possible to gain stereo vision later in life. I suspect that there are some vision therapists that are exceptional. I also suspect that most are not. There are many simple and inexpensive tools that can help such as two strings with beads (Brock String) and polarized sheets with circle images all of which you should already know about. Without special funding, I doubt there is any hope for a game developer to create a video game for vision therapy specific to strabismus. Given how boring treatment can be I suspect an 8 year old has little enthusiasm for conventional methods and a video game would be an exceptional tool! The internet is your best friend and I’d recommend seeking out other parents and start social networking groups and make it happen! Stereo vision is extraordinarly important and life changing. Anyone who tells you different is ignorant and should be ignored. Please don’t give up and don’t accept your situation. Change it! The internet is your friend and tool… use it for all it is worth and for all of the children with Strabismus. Seek out a game developer and work out the costs and find a willing and top notch therapist to supervise and create a foundation to raise money. You can do it and you can find help. You wrote to me, and that is the first step. I don’t know about video game development and I don’t know a suitable vision therapist but I am positive you can find those people on the internet. Give it a go, and if you have no luck email me and I’ll try and help. But I suspect you will be surprised at the number of good people out there waiting for someone like you to prod them into helping you taking action. If you haven’t read Susan Barry’s book “Fixing My Gaze” please read it! It will help you a great deal.

  4. Kelly

    I found out about Susan’s book because I am very concerned for my husband. He may lose his Air Force job that he has held for 13 years as a loadmaster. The reason is that the Air Force has just added that an airman’s inability to see in stereovision is no longer a waiverable item on the vision test. Even though the position does not require scanning duties, my husband’s job is still in jeopardy. He is desperate to keep his job. Just in case pleadings do not work, I suggested to him to train his eyes and brain to see correctly so he can pass these tests. He has flunked these tests throughout his career but was always able to get a waiver. Not any more and now we are both fighting for his job. My five year old daughter, I believe, has the same condition as she has a strabismus and had her eyes operated on when she was two. Her right eye turns in when she is tired or when she is focusing and I am going to read the book so I can understand both of their conditions. I plan to read the book and others and get them both the vision therapy that they need so my husband can keep his job and my daughter will not be limited on what she wants to do when she grows up! I am pleased to hear that you can train your eyes and that its not too late. It all depends on how motivated you are and willingness to work hard. My husband is very motivated and I will post here and let you know what success we have and if he does get to keep the job he loves.

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