Oliver Sacks discusses sterovision, amusia, and how his books come together.

Oliver Sacks: Some years ago, when I was actually interested in writing about astronauts and what the zero gravity experience was like, I met an astronaut’s wife at a party and observed something a little odd about her gaze. And she said, yes, she had in fact been born cross-eyed, with a squint, and that this had been treated surgically.

Most people didn’t notice anything the matter, but I, with my indiscreet neurological eye, had observed something. She said that both eyes worked perfectly, but, in fact, one eye would work at a time.

And I asked if she could imagine what it would be like having the eyes aligned together and seeing stereoscopically, in depth, which she had never done.

Although, she said, she was a good athlete, she was sometimes teased by normal athletes by suggesting they wear a patch on one eye, and she didn’t feel that anything much was missing.

And she said, sure, she could imagine stereovision. She said she was a scientist. She had read all the original papers. She could imagine it.

So, I let it go. But then, 10 years later, she wrote me a letter recalling this conversation and saying, “No. I was wrong.” And she said she was wrong because she said now she had stereovision. She described how it had been given to her through some special exercises and prisms in her glasses, and she was ecstatic about it.

She described how it had first occurred. She’d come out of her training session. She’d gotten to her car. She said the steering wheel had suddenly popped out from the dashboard, and she thought it was some strange mirage at first, and then she closed one eye and then the other, and she realized this was it. This was stereovision. This was what everyone had, although they sort of took it for granted, and for her it was wonderful.

And she said, you have to have been stereo blind for 50 years and then have it, and she imagined it would be like being totally colorblind, being in our colorless world and suddenly seeing color.

Anyhow, I was fascinated by this, especially as it is said that one has to have stereovision by the age of two or you’ll never have it, and here was someone of 50 who said she developed it.

So I went along with a couple of friends and colleagues. I paid her visit. She lived up in a small town in Massachusetts. I tested her carefully.

She had kept a wonderful visual diary, which was just full of wonderful descriptions, newly minted descriptions of the world of someone in a snowstorm, or seeing a tree, seeing faces for the first time as they should be seen.

I was particularly interested in this because I’d always had a passion for stereo photography myself. And I was a member of the New York Stereoscopic Society, which is one of the many eccentric societies in New York, and we would go on stereo weekends and things like this.

And I’m also interested in stereovision in animals. For example, something like a cuttlefish has its eyes on either sides, so it gets panoramic vision, but when it goes in for the kill, the eyes are brought forward, and then the tentacles are shut out. And when the eyes are brought forward, then it gets stereovision.

So what with her letter and my own interest, and being interested in cuttlefish and squids and things, so this all came together in a piece, which was partly about her, partly about myself, partly about the history of photography, partly about animals with stereovision.

So that’s the sort of the strange mixture which occurs with me.

Recorded on: Sep 4, 2008