Susan R. Barry is a professor of neurobiology at Mount Holyoke College and the author of Fixing My Gaze: A Scientist's Journey into Seeing in Three Dimensions. Barry was dubbed Stereo Sue by neurologist and author Oliver Sacks in a 2006 New Yorker article with that name. Barry's book greatly expands on Sacks' article and discusses the experience of gaining stereovision through optometric vision therapy, after a lifetime of being stereoblind. It challenges the conventional wisdom that the brain is wired for perceptual skills during a critical period in early childhood and provides evidence instead for neuronal plasticity throughout life. Barry's achievement of stereo vision, with the help of a developmental optometrist Dr. Theresa Ruggiero, was reported in a BBC Imagine documentary broadcast on June 28, 2011.
Barry had been affected by alternating esotropia since early age, and had undergone corrective operations to her eye muscles at two, three and seven years of age. At the age of forty, she became aware of difficulties in correctly perceiving objects at a distance, such as road signs and faces. The ophthalmologist whom she consulted told her that her eyesight of both eyes had only small flaws which were already corrected by her eyeglasses. Years later, after a colleague drew her attention to her tendency to disregard raised hands at the back of the large classroom, she consulted an optometrist who referred her to Ruggiero. With her, Barry embarked on vision therapy to stabilize her gaze. using the approach developed by Frederick W. Brock, including for example exercises to aim the two eyes at the same point in space using the Brock string. She first saw 3D at the age of 48 sitting in the driving seat of her car after a session of vision therapy. In her own words she describes her experience as seeing the steering wheel "floating in front of the dashboard with this palpable volume of space between the steering wheel and the dashboard". It took her months to accept that she truly had stereo vision "because of all of the scientific dogma that indicated that this was not possible". She contacted Oliver Sacks, with whom she had spoken of stereopsis at an earlier occasion. Together with ophthalmologist Bob Wasserman and vision physiologist Ralph Siegel, he came to visit her and Ruggiero in February 2005, and in 2006 he published an article on their story in The New Yorker.
Challenging earlier views
Barry had initially found it difficult to believe in her acquisition of stereo vision for the reason that the notion of critical period was firmly set since the groundbreaking work of Torsten Wiesel and David H. Hubel with deprivation experiments in which animals did not develop the neuronal basis for stereo vision if they were prevented from performing stereo fusion for a given time period after birth. Barry contacted Hubel, who had no difficulty in believing in her vision improvements and stated that their experiments in fact had not addressed the question whether the animals might have been able to recover stereo vision later. Hubel further suggested that newborns may be already equipped with binocular depth neurons. In her book Fixing my Gaze, Barry points out that Wiesel and Hubel's results were mistakenly extrapolated, not by Wiesel and Hubel themselves, but by the majority of scientists and physicians, who mistakenly assumed that the critical period for developing amblyopia also applied to the recovery from amblyopia. She concludes:
Other cases of acquired stereo vision
After the article on "Stereo Sue" was published, Barry found and took up contact with a number of persons who shared with her their own stories of lacking and acquiring stereo vision. She reports on their experiences at regaining 3D vision in her book Fixing my Gaze. Apart the cases recounted by Barry, further cases have been pointed out recently in which a formerly stereoblind adult has acquired the ability for stereopsis. This happened also to neuroscientist Bruce Bridgeman, professor of psychology and psychobiology at University of California Santa Cruz, who had grown up nearly stereoblind and acquired stereo vision spontaneously in 2012 at the age of 67, when watching the 3D movieHugo with polarizing 3D glasses. The scene suddenly appeared to him in depth, and the ability to see the world in stereo stayed with him also after leaving the cinema.
Awards
The Princeton Review lists Barry among the 300 outstanding college teachers in the U.S., her paper on the work of Frederick W. Brock was selected as the best published paper in the Journal of Behavioral Optometry in 2011, and in 2013 she received the Meribeth E. Cameron Faculty Award for Scholarship.
