What Oliver Sacks Taught Me

What do you do when your own observations contradict common beliefs or entrenched dogma? Do you dismiss your observations as biased and flawed, or do you question authority? This was the question I asked myself when I experienced a remarkable change in my vision. I had been cross-eyed and stereoblind since early infancy but, thanks to optometric vision therapy, learned to coordinate my eyes and see in 3D at age 48.

Yet, my visual experiences were considered impossible. They contradicted a half-century of scientific wisdom that indicated that stereovision could develop only during a “critical period” in early childhood. What’s more, my new way of seeing provided a much more dramatic change in worldview than I or most vision scientists expected. Stereovision was thought to improve our sense of depth primarily in near space, but my whole world transformed. Space expanded. I could see the volumes of space between tree branches and falling snowflakes. The world appeared less cluttered; objects more spread out. In my stereoblind years, I felt that I was looking in on the world but now found myself immersed in my three-dimensional surroundings. I wanted to tell the whole world my story but was afraid that scientists and doctors would dismiss my experiences as exaggerated, overly dramatic, and perhaps even delusional. What to do? I could think of only one good answer: Write a letter to Oliver Sacks.

“Can you imagine what it’s like to see with two eyes?”

I knew Dr. Sacks first from his books and admired the way he wrote about his patients with such insight and empathy. But also, I had met him once in person. As we talked during our brief five-minute conversation, I became aware of the way Dr. Sacks was looking at my eyes. I knew that he knew I was cross-eyed. So I told him that I saw the world differently than most. I had good vision in both eyes, but I used only one eye at a time and did not see in 3D. That’s when Dr. Sacks asked me a question that haunted me from that time forward: “Can you imagine what it’s like to see with two eyes?” He didn’t ask “Can you see the 3D in a 3D movie?” or “How do you score on stereovision tests in the eye doctor’s office?” Instead, he asked me if I could imagine seeing in 3D. In other words, he wanted to know what it was like to be in my head, to see what I saw and think what I thought.

I answered Dr. Sacks’s question casually, saying that I believed that I knew what it was like to see in 3D. After all, I was a neurobiology professor and had read plenty of scientific papers on stereopsis. I gave my students stereovision tests to try and thought I knew what I was missing. But once I began to see in 3D, I realized how wrong I had been. My theoretical knowledge of stereopsis did not prepare me in the least for the experience of seeing in stereo. Dr. Sacks must have suspected that stereopsis would provide me with an astonishing new way of seeing, one that I could not even have imagined. Sacks may not have been an eye doctor, but he was a physician who had spent his life trying to imagine what the world was like for his patients. While objective data from clinical tests may teach us a lot about a person’s condition, to understand how that person lives day by day, we also need to gain a sense of the patient’s inner world—their memories, perceptions, feelings, and thoughts.

"Stereo Sue"

In 2004, about two years after my vision transformed and nine years after Oliver Sacks asked me his question, I finally wrote a letter to Sacks but only sent it after much encouragement from my husband. Oliver later told me that the letter made his hair stand on end. He wrote back right away, came to visit me at my home, and wrote a story about me titled “Stereo Sue” that appeared in The New Yorker and later as a chapter in his book, The Mind’s Eye. In a painful twist of fate, just as “Stereo Sue” was going to press, Oliver began to lose sight in his right eye and ultimately lost stereovision. As we continued to exchange letters about our own contrasting visual experiences, how space expanded for me and collapsed for him, Oliver contrasted the information obtained from clinical tests of 3D vision with our personal impressions. He wrote to me, “I think these quantitative or behavioural measures ... miss the point—and that it needs, not behavioural tests, but descriptions of individual experiences (like yours and mine) as well.” Our subjective experiences matter.

By listening so attentively to my story, Oliver gave me the confidence to trust my own observations and to unleash those powers of observation on everything and anything. Whenever I encountered something exciting or learned something new, whether it was about vision, plants, animals, music, or the brain, I found myself composing a letter about it to Oliver. I simply couldn’t stop writing to him, and he, in turn, responded with his own musings and drafts of the material he was working on. Over a 10-year period, up until three weeks before his death, we exchanged 150 letters. After Oliver passed away, I had to find a way to handle my sadness. So, I revisited all our letters and wrote a new book, Dear Oliver: An Unexpected Friendship with Oliver Sacks, as a tribute to exploration, letter-writing, friendship, and Oliver Sacks.