MICHELE NORRIS, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.
This next story is about a blind man who discovers he can still see. Here's the twist: What he sees isn't there.
This little mystery comes to us from our science correspondent Robert Krulwich.
Mr. DAVID STEWART: It's such a bore, (unintelligible). Don't ever do it.
ROBERT KRULWICH: Okay.
David Stewart went totally blind when he was around 70, about 10 years ago. So I wonder…
Mr. STEWART: Oh, how did I get blind?
KRULWICH: Yeah.
Mr. STEWART: I became blind because I'm the unlucky winner of a genetic sweepstakes called retinitis pigmentosa. It's a dying off of rods and cones of the eye.
KRULWICH: And it runs in his family. It happens gradually.
Mr. STEWART: And slowly, slowly, everything eventually disappeared.
KRULWICH: Until one day, something kind of odd happened.
Mr. STEWART: I was reading, which in my case, means listening to a book on tapes.
KRULWICH: "1776" by David McCullough, which describes in part how American sailors helped George Washington during the revolution.
Mr. STEWART: And I found that very intriguing. In any event…
KRULWICH: Just as he was thinking about those sailors, he suddenly had a vivid hallucination. A man wearing a sailor cap just appeared in his head.
Mr. STEWART: There he was, he had on a cap, a blue cap with a polished black beak, and he had a pipe in his mouth.
KRULWICH: Kind of wavy ghostly or kind of vague…
Mr. STEWART: No.
KRULWICH: …or was he a precise…
Mr. STEWART: No, he's quite precise.
KRULWICH: And then this very real-looking man looked right at David somehow and blinked.
Mr. STEWART: Yes.
KRULWICH: Did you like freak? Did you go…
Mr. STEWART: No, no, no. No. It wasn't spooky, whatever. It was just that he was there. I acknowledged his presence. He acknowledged mine, so.
KRULWICH: And you knew that this guy wasn't real. Some part of you knew he…
Mr. STEWART: I knew that it wasn't real. That's right.
KRULWICH: How come?
Mr. STEWART: I don't know.
KRULWICH: So, how long did the sailor stay in your head?
Mr. STEWART: He stayed for, oh, I suppose, half an hour.
KRULWICH: Half an hour.
Mr. STEWART: And then he faded away. But I don't recall the fade, you see.
KRULWICH: But after he faded, later on David then saw imaginary patterns. Then, imaginary paintings, imaginary curtains. They kept coming.
Mr. STEWART: At least once a day.
KRULWICH: So, of course, he went to the doctor. And he was told, no, you're not crazy.
Mr. STEWART: You have almost certainly Charles Bonnet syndrome.
KRULWICH: Charles Bonnet is a condition that affects people with macular degeneration or diabetic eye disease. When you lose your sight, says Jonathan Trobe, a neuro-ophthalmologist of the University of Michigan, some people start seeing things. It is, he says…
Dr. JONATHAN TROBE (Neuro-ophthalmologist, University of Michigan): Very common.
KRULWICH: Sometimes scary…
Dr. TROBE: But more often, patients describe rather pleasant hallucinations like flowers or pictures or beautiful blue sky.
KRULWICH: Astonishingly vivid people like David's sailor are not really typical.
Dr. TROBE: The winking at him, that's not usually something that we hear.
KRULWICH: But there are enough cases. Dr. Trobe thinks maybe 10 percent of all people who go blind will hallucinate. And the explanation, he says, is that when cells in your brain dedicated to seeing aren't getting information -because after all, you are blind, your eyes aren't working - since nothing is coming in to the seeing part of your brain, the cells up there look for something to do, so they hallucinate. They take memories and mix them into fantasies that aren't there.
Dr. TROBE: That's right. The brain is doing a mash-up of stored visual memories. And they come out when the external stimuli are taken away.
KRULWICH: As evidence, in 2004, scientists at Harvard University blindfolded normal-sighted people. And within hours, many of them began to see imaginary landscapes and patterns. One woman, he says…
Dr. TROBE: After being blindfolded for a day or two, said that she saw Elvis…
(Soundbite of laughter)
KRULWICH: Of course.
Dr. TROBE: …appear in front of her.
KRULWICH: And these hallucinations, by the way, are often in color. So after years of being blind, David had almost forgotten what color was like. But when he saw his sailor…
Mr. STEWART: There it was. The first color I had seen for a considerable amount of time.
KRULWICH: And he loves color. So his hallucinations are now such a pleasure, he has figured out how to have them more often. When he was losing sight, his eye doctor advised him to eat fish so he wouldn't get worse. And that's when he discovered that tuna sashimi helps him hallucinate.
Mr. STEWART: Yeah. Not all the time.
KRULWICH: What else? So you can eat your way into your hallucinations?
Mr. STEWART: Yes, so it appears.
KRULWICH: But when I asked Dr. Trobe is there any scientific support for sashimi-induced hallucinations, he said…
Dr. TROBE: No. How about that for a short answer?
KRULWICH: But I couldn't resist. And how could you not try? So, midway through our interview…
Dr. TROBE: You do come equipped, I have to say.
KRULWICH: Yeah.
I gave him some sashimi.
Mr. STEWART: Okay. Hmm. Lovely.
KRULWICH: And we kept on talking. And then about 10 or 12 minutes later, while discussing his green curtain hallucination…
Dr. TROBE: If you have multiple-curtain hallucinations?
Mr. STEWART: Yes. Yes, I have. I did a lot of work in a theater and that may…
KRULWICH: Very matter-of-factly, he said…
Mr. STEWART: There is my curtain right there.
KRULWICH: I knew the fish would work.
Mr. STEWART: Right. Yes. By golly, you're right.
Dr. TROBE: Don't be frightened, Robert.
KRULWICH: This was so strange. Where did these hallucinations come from? A minute later, he saw a pink dress.
You don't wear dresses?
Mr. STEWART: Not anymore. No, I never did.
KRULWICH: So, where would a pink dress - why a pink dress?
Mr. STEWART: I have no idea where that comes from.
Dr. TROBE: I think that what you hallucinate often has to do with what you got in you and what you've experienced and what you're able to report.
KRULWICH: These hallucinations, as vivid and strange and common as they are, are so personal, says Dr. Trobe, they become a comfort. So I asked David, if I could give you a pill that would make these hallucinations go away completely and totally, would you take the pill?
Mr. STEWART: No. But if you have one that prolongs, I would take it in a minute.
KRULWICH: Because for David, these hallucinations have become his new way to see.
Mr. STEWART: It's not much.
KRULWICH: But he'll take what he can get.
Robert Krulwich, NPR News in Washington.
NORRIS: Robert Krulwich points out that blind people aren't the only ones who have hallucinations. Deaf people hallucinate sounds that aren't there. Amputees hallucinate limbs that aren't there. Brains make stuff up. In fact, Herman Melville, in his novel "Moby Dick," tells a hallucination story. His sea captain, Ahab, is missing a leg because a whale ate it. And at chapter 108 in the book - and you can look this up - he says to a friend, "I know my leg is missing, and yet for some reason, it feels like it's still there, still part of me." "You can feel your leg, right?" he tells his friend. It feels attached. And then he says - and I'm quoting here - "Where thou feelest tingling life; there, exactly there, there to a hair, do I. Isn't it a riddle?"
A riddle indeed. Captain Ahab's brain was behaving just like David Stewart's brain - compensating for a loss.