Susan R. Barry, Ph.D., is a professor of neurobiology in the Department of Biological Sciences at Mount Holyoke College. She had been cross-eyed and stereoblind since early infancy but learned to see in three dimensions at age forty-eight by retraining her visual system with optometric vision therapy. Her story was first described by Oliver Sacks in his New Yorker article, Stereo Sue, and then greatly expanded by Sue in her book, Fixing My Gaze: A Scientist's Journey Into Seeing in Three Dimensions. Sue's book challenges the conventional wisdom that the brain is permanently wired for basic perceptual skills during a "critical period" in early childhood and offers instead a revelatory account of the brain's capacity for change.
Susan Barry: My first 3D experience happened after a vision therapy session in my developmental optometrist’s office. When I went out to my car and I sat down in the driver’s seat and I looked at the steering wheel to drive away, and the steering wheel was floating in front of the dashboard with this palpable volume of space between the steering wheel and the dashboard. And I had never seen anything like that before. And I thought, “Is this stereovision?”
And then I thought, “No way.” The day happened to be the day after my 48th birthday. So I knew I was more than 40 years past the critical period -- that window of opportunity when one can develop stereovision. And I thought to myself, “It must be the sun coming . . . the sun rays coming into the car at an odd angle” -- because it was right around sunset – “that’s giving me this strange illusion.” And I closed one eye and the steering wheel looked normal again.
That is, I knew it was in front of the dashboard because the steering wheel itself blocks a little bit of my view of the dashboard. But it didn’t look like it was in front of the dashboard with this pocket of space between it and the dashboard. And then I opened the two eyes again, and there was the steering wheel floating before me. And I thought, “This is just some crazy illusion. Just concentrate on driving and get home.”
And so the next day I got up and I did my vision therapy exercises, and I got into the car and I went to adjust the rearview mirror. And when I did that, it was floating in front of the windshield. I thought, “Whoa, again! What’s going on?” And I went into work and everything began to transform -- not just that day, but over the next number of months. So, for example, a sink faucet would just seem to be sticking out toward me like this.
And I can remember going into the bathroom at Mt Holyoake College, where I work as a professor. And there was a student in there and I said to her, “Look at that sink faucet.” And she kind of looked at me like I was nuts. And I said, “The arc of that sink faucet’s like the most beautiful arc I’ve ever seen” because I could see it emerging through these layers of space in 3D. And of course, the student didn’t know what to think of all this, and she just turned tail and kind of ran right out of the bathroom.
So it was experiences like that that was so novel, so surprising, that made me think perhaps this really is stereovision. But you know, it took me months to really accept that that was the way I was seeing because of all of the scientific dogma that indicated that this was not possible.
So some of the things we know now about the malleability of the brain in general are this: that if you do functional MRI or other brain imaging studies on people and you give them a task to learn, you can see that areas of their brain change -- the way the brain is activated changes --, that we have maps in our brain, for example, of our own bodies and these maps are distorted in the sense that parts of your body for which you need to have extra good sensory perception, let’s say your fingers versus your thigh, the maps of the body for those places where you want to have extra good sensory perception are larger.
More neurons are devoted to those areas than other parts of your body. And those maps can change depending on how you use your hands versus your legs, and so on. So we now have evidence that the human brain can change and can change relatively rapidly, within days, maybe even hours. Okay?
A second piece of evidence that we have now is molecular and cellular evidence showing what happens to neurons in the brain and to the connections or synapses between those neurons. And we now have an understanding of what some of those changes may be. In order to change the way the brain works, you have to change the strength of those synapses. And now we have some ideas of what those mechanisms may be.
In my case in particular, I think one of the things that held back the realization that somebody with my condition, crossed eyes, or related conditions, wall eyes, lazy eye, also called amblyopia . . . one of the things that kind of held back an understanding of this, that a person could improve their vision in these ways, had to do with the fact that the patient, the patient with the visual problem, was always sort of relegated to a passive role. So, for example, in my case, I had strabismus, I didn’t use my eyes in a normal way. I didn’t look straight with the two eyes so surgeries were done to make my eyes look straighter, but I could never have learned to see in 3D unless I actually did the straightening of my eyes.
So I was the one who had to learn how to turn the two eyes in together at the same time to fixate that close object and how to turn the two eyes out at the same time to, let’s say, fixate on objects in the distance, like your face. I was the one who had to learn how to make those movements. And it was only after I learned how to make those movements that I was able to see in 3D. So, a change in my action had to precede a change in my perception.
And I think we are realizing that more and more, that action and perception are just very, very intimately linked. You can’t really separate one from the other. And for changes in the brain, often what has to happen are this sort of constant dialogue between changing action, changing perception, changing action and so on.
Directed / Produced by Jonathan Fowler & Elizabeth Rodd