The human brain is really coming along. Time was, and it wasn’t so long ago, that scientists figured that if you didn’t learn an essential skill when you were a kid, you weren’t going to learn it at all.
That may still be largely true of language (unless you’ve had the acquisition window propped open by early multi-language learning): unless you get it while young, you’re going to work like a dog to learn to speak another language and likely will never learn it well enough to sound like a native.
The same was long held to be the case with seeing in three dimensions. As Oliver Sacks writes in his introduction to Fixing My Gaze, what Susan Barry experienced “went completely against the current dogma of ‘critical periods’ in sensory development... [Stereoscopy] had to be acquired in the first three or four years of life, or it could never be acquired, for the critical brain cells and circuitry needed for stereovision would fail to develop.”
Lucky for Barry, dogmas are easy to run over with the truck of empirical experience. More or less born cross-eyed and thus lacking in stereovision, Barry spent most of her young life unaware of what she was missing. In college, though, she was sitting in a neurobiology lecture as the professor described the development of the visual system. As he described the inability of kittens with strabismus (misaligned or crossed eyes) to ever see stereoscopically, even after their eyes were straightened, Barry was thunderstruck: that was exactly her situation.
Barry went on to become a respected neuroscientist, her life and career unhampered by the fact that she lacked stereovision. But Barry never gave up hoping that she could somehow regain 3D sight. Eventually she found an optometrist who prescribed an unconventional regimen of vision therapy. And, after intensive training, she one day emerged from a dim Manhattan subway into bright daylight and saw the world in a new way. A stereoscopic way.
The change in vision flabbergasted her, as much for what she hadn’t been seeing for over 40 years as for the death of the dogma that severely constrained her therapeutic options.
The story of Barry’s breakthrough into stereovision occupies the first few pages of Fixing My Gaze. What follows is, in part, a stake being driven through the heart of dogma, as well as a well-written account of the neurobiology of vision. Barry’s book is great for anyone interested in learning more about the fascinating and complex biology of seeing, as well as those seeking hope and inspiration in overcoming a brain-centered disability thought to be incurable. While it’s true that no two patients are the same, Barry’s story underscores the truth that dogma is never a viable prescription.