Oliver Sacks is a practicing neurologist and professor of neurology at New York University School of Medicine.* He was born in London but has lived in New York since 1965. He is the author of The Man Who Mistook His Wife for a Hat, and his latest book is Hallucinations.
Tiffany O’Callaghan: Your latest book is about hallucinations. Why did you want to write about them?
Oliver Sacks: I've been fascinated with them for a long time. I've touched on hallucinations in different ways in earlier books, but there's such a vast variety, and there are so many causes, so much misunderstanding—and sometimes so much stigma attached—that I thought it would be good to bring things together. An additional reason has been the beautiful neuroimaging in the last 10 years or so, which confirms that at least simple hallucinations tend to arise in sensory areas which normally serve perception.
TO: You mentioned stigma. Do most people associate hallucinations with mental illness?
OS: I think there's a common view, often shared by doctors, that hallucinations denote madness—especially if there's any hearing of voices. I hope I can defuse or de-stigmatize this a bit. This can be felt very much by patients. There was a remarkable study of elderly people with impaired vision, and it turned out that many had elaborate hallucinations, but very few acknowledged anything until they found a doctor whom they trusted.
There are all sorts of situations in which one may have hallucinations. Many people have hallucinations of a sort before they fall asleep or sometimes just after waking.
TO: What is the difference between hallucination and imagination?
OS: I think you recognize that what you imagine is your own, whereas with hallucinations there is no sense of you having produced them. One feels, "What's that? Where did it come from?"
I saw this very clearly many years ago in an old lady who started to hear Irish songs in the middle of the night. She thought a radio had been left on but couldn't find the radio. She then thought that a tooth filling was somehow acting as a transistor. Finally, when certain tunes kept repeating themselves, all tunes that she knew, she wondered if it was a sort of radio inside her head, a mechanism not under her control, and apparently not related to what she was thinking or feeling or doing. That way of putting things is very common in people with musical hallucinations.
TO: In the book [Hallucinations], you share experiences of your "lost years" in California in the early 1960s, when you tried lots of drugs. Why write about this now?
OS: The primary reason is that what happens with me is a potential source of information. I will, as it were, use my own case history as I will use other people's. But perhaps again the fact that these were encapsulated in a time period, say, between 1963 and 1967, more than 40 years ago, made me feel easier about describing them.
TO: You experimented with LSD and other hallucinogens. Have those experiences informed your work as a neurologist?
OS: I think it made me more open to some of my patients' experiences. For example, there is something which I think of as stroboscopic vision, or cinematic vision, where, instead of seeing a scene continuously, you see a series of stills. I've had that myself on LSD, I've had it in migraine, and my patients taking L-dopa sometimes describe it, too. So rather than saying nonsense, or closing my ears, I am open to these descriptions. Whether these psychedelic drugs made much difference to me otherwise, I don't know. I'm glad I had the experience. It taught me what the mind is capable of.
TO: One time you had a conversation with a spider ...
OS: With the spider, I should have known that it's impossible. That's one of the few times when I was completely taken in. The business of believing and being converted by hallucinations worries me. For example, a book has just been published by a neurosurgeon who had a so-called near death experience and is convinced that he saw heaven. I want to say, strongly, hallucinations aren't evidence of anything, let alone heaven.
TO: You highlight a tendency for hallucinations, particularly those caused by epileptic seizures, to feel like religious experiences. Why is that?
OS: Hallucinations can be very powerful and very persuasive. I think one may have to fight to deny them weight. There was one case history which I should have put in the book. A young woman, a physician, had some of these seemingly revelatory seizures, but she argued with God. God said: "Don't you believe your senses?" She said: "Not when I'm in a seizure."