I ordered this new book just after meeting the inspirational Dr. Barry at this year's meeting of the Vision Sciences Society. The book arrived this last Friday and I spent the day reading it. I confess to be blown away by her story, as well as the scientific and clinical implications of her work. Add me to the list of people who loved the book!
Sue Barry's astonishing development of stereopsis at age 48 changed - profoundly - the way that many scientists (me included) view visual development and plasticity. Somehow we had tuned out, en masse, one hundred years of successes using vision therapy (including the extensive the work of Frederick Brock). The stuff of vision therapy was ignored, relegated to the fringes of sensible vision care. Instead, several generations of us took the Nobel Prize winning research of Hubel and Wiesel as gospel truth, going beyond the data by wrongly concluding (perhaps unlike the Nobel laureates) that stereopsis could only develop during a critical period during infancy. It took Barry, a well-established neuroscientist and keen observer, to bring us to our senses.
And yet now, having read her new book, I see that the story is much deeper and profound than I thought. First off, she's a very entertaining storyteller in her own right. The human drama escalated as she went through frightening surgeries as a child (including an encounter with a deceptive anesthesiologist); as she experienced shock and disappointment at being exposed as stereoblind; as she had her vision problems dismissed by one ophthalmologist as a psychiatric disorder; as she experienced steropsis bursting out at her for the first time; as she gained steam and knowledge, recognizing the scientific, clinical, and human implications of her story; as she brought celebrity neuroscientists on board. And so it is a story of empowerment for Barry the patient, Barry the scientist, Barry the teacher, and Barry the instiller of hope.
I believe that Susan Barry has demonstrated for many of us that stereopsis is, indeed, important. I, for instance, was trained to believe that binocular vision and any advantage it afforded us wasn't that big a deal. Sure, I loved stereo viewers and all that... But as an undergrad at Berkeley in the early `80s, I recall a visit by Bela Julesz, of cyclopean vision fame. Two of my academic heroes, Russ and Karen De Valois rose to challenge Julesz, eventually (as I recall) suggesting that two eyes really aren't that much better than one. As I read Barry's book, as well as her descriptions of the consequences of her visual deficit, I realized that my early academic training (as a I had encoded it) was quite wrong. The book makes it clear that lack of stereopsis, and having two eyes that don't fuse images properly, has profound consequences for people like Barry (e.g., her driving, her energy level, and her sense of efficacy). Moreover, it is fair to say that Barry is an extraordinary observer of stereoscopic experience, and that she uses her newfound, developing perceptual ability to achieve scientific and clinical insights that are elusive to us who grew up with normal stereopsis.
One of the epiphanies for me was when I read and grasped the following paragraph: "Just as I could not imagine a world in stereo depth, an individual with normal normal stereopsis cannot experience the worldview of a person who has always lacked steropsis. This may be surprising because you can eliminate clues from stereopsis simply by closing one eye. What's more, many people do not notice a great difference when viewing the world with one eye or two. When a normal binocular viewer closes one eye, however, he or she still uses a lifetime of past visual experiences to re-create the missing stereo information."
People interested in stereopsis will find excellent coverage of the basic issues and the key scientific figures past and present (e.g., Wheatstone, Hering, Helmholtz, Eileen Birch, Shin Shimojo, Denis Levi, Uri Polat, Chris Tyler). It is nice, if not surprising, to learn that the already positive, cool Oliver Sacks played a positive, cool role in Susan Barry's story.
If you have strabismus or some other disorder of binocular vision, you will find what you need here. You will find out how to find an appropriate vision therapist. You will find extensive, understandable information about the theory and science of binocular vision. More importantly, you will learn in marvelous detail about the experiences and practices that can in some instances lead to acquiring stereopsis late in life. My guess is that vision therapy patients will use this book as a guide for years to come.
One last thing: I recommend listening to two NPR interviews (2006, 2009) featuring Sue Barry, as well as other key scientific figures in the story, including Sacks, Hubel, Levi, and, briefly, the heroic Theresa Ruggiero. The NPR programs are available online and go quite well with the book.
Two thumbs up! (one with uncrossed disparity; one with crossed disparity).