The Itching Question That's More Than Skin Deep

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Studies show that the power of suggestion can induce itchiness — but scientists don't know what this irritation is, what causes it, or why it feels so good to cure. Marc Abrahams, editor of the Annals of Improbable Research, talks about how talking about the science of itches might have you scratching right now.


Next up: Mosquitoes, chickenpox, sheep wool. People can name a hundred things that can make them itchy, but no one can tell you why. It's had scientists scratching their heads for years. Has it got you scratching yours? Studies show that just by listening to, say, a radio broadcast talking about certain uncomfortable sensations could have you squirming in your seat. Fighting to scratch that itch already, yeah? On the phone is Marc Abrahams, editor for the Annals of Improbable Research. He's going to tell us why you may already feel like scratching. Welcome to SCIENCE FRIDAY, Marc.

MARC ABRAHAMS: Hi, Ira. Are you scratching?

FLATOW: I'm wondering, how many people out there - is the power of suggestion, does it work in scratching?

ABRAHAMS: That was the big question. Scratching and itching are really mysterious. For as long as people have been digging into the nervous system, trying to figure out how the brain and nerves work, they've been looking at itching and scratching as great mysteries. There have been lots of explanations, but nobody really knows how they work. And there have been, in the past 15 years, two studies that got at the big question of how much of this can happen just by suggestion.

FLATOW: Hmm. And in other words, if we get a group of people together and sort of suggest something that's scratchy, they'll start itching?

ABRAHAMS: Yeah, yeah. So there was one study that was done about 10 years ago in Germany. They invited a lot of people to come to a movie theatre. They were told that this was going to be filming a TV show. And they were shown, first, a bunch of slides of things that were thought to induce itching. They weren't told to itch or anything, but they're just shown these things. And then after that, they were shown a bunch of other slides of things, like babies and soft down and soft skin that were thought to make people relax and be not itchy. What was really going on was the TV cameras were focusing on the audience, and they were recording the audience.

And afterwards the scientists had a bunch of people look at the video tapes and try to very carefully take records for each person in the audience of how often they scratch. And what they found, they say, is that while watching those slides of really itch-inducing things, people did scratch themselves a lot more. And then when they started to see the slides of nice soft babies and things, they stopped scratching to a degree. So that was one experiment. About five years before that, in the U.S., at Indiana State University, there was a guy named Mitchell who was working on his Ph.D. dissertation, and he, on the surface, was interested in subliminal suggestions, you know, those old stories - you go to a movie theater and they stuck in these real quick flashes of words that say buy popcorn. And the old stories are that people would rush out and buy popcorn, and nobody is sure that ever happened. So he was trying to look at this, and he got itching and scratching involved because he wanted some way that was inarguably evidence.

And so he prepared some audio tapes, and one audio tape had subliminal messages of scratching, people saying scratch and itch and things like that, but recorded - the words were recorded so softly nobody could detect them, nobody could hear them, and then they put some music on top of that. So that was one group of people listening to that tape. Second group of people listened to a tape of just the music with no subliminal suggestions. And then a third group listened to a tape that had just somebody overtly saying, itch and scratch, and the results came out not what they expected exactly. Results came out on the subliminal tape, almost nobody was itching. And most people were itching on the tape that had just music, and not so many were itching on the tape that was telling you to itch. So it was quite mysterious.

And the result of both of these things, when you add them together, is that it's pretty much where people started. Nobody really understands a whole lot about how itching ties in with suggestions. Now, this sounds like funny stuff and probably is, but on the other hand, there are a lot of people who suffer from itching, and it can be a terrible, horrible thing that goes on and on and can ruin people's lives. And doctors really, for the most part, don't know what to do about that.

FLATOW: Interesting. Talking with Marc Abrahams on SCIENCE FRIDAY from NPR about studies about itching and scratching. One other study that is interesting - and I'm itching right now.


FLATOW: I wonder how many of the people are itching as we're talking.

ABRAHAMS: I don't intend to make you too much more uncomfortable, Ira, but could you tell me exactly where on your body you are itching.

FLATOW: I'm itching on my back.

ABRAHAMS: Your back?

FLATOW: My back.

ABRAHAMS: OK. There's an experiment that was done recently. It was published just a few months ago, and it was done in, I think, four different countries, in the U.K., Saudi Arabia, United States and Singapore, I think, was the fourth one. And they were scratching people, and they're trying to figure out, you know, there's some pleasure involved...

FLATOW: Right.

ABRAHAMS: ...when you finally do scratch. So they're trying to measure that part of it. So they had some people who were trained to do the scratching using special brushes, and they would have them scratch on three different body parts. And periodically they would ask the person who is being scratched to indicate, you know, a scale of one to nine, I think, how pleasurable it was. And what they ended up discovering, they said, was this really is very different on different body parts. They measured the forearm, the back, and then they also scratched on people's ankles. And they found that there's a great amount of pleasure initially when you start scratching any of those places. But the only place they found where the pleasure keeps on - you can keep scratching for a long time, and it stays pleasurable, is on the ankle.

FLATOW: Wow. Ah.

ABRAHAMS: And nobody really knows why.

FLATOW: You can scratch - in other words, you can satisfy the itch on the back and the arm, but you can keep scratching your ankle, and it still feels good.

ABRAHAMS: Yeah, so exactly that. The first two, you satisfy it, but it's just satisfied. The third one, you're getting some pleasure. And also, nobody really has any clear idea whether this is tied to something important or trivial or what. It's really a deep mystery.

FLATOW: Wow. So scratch - so, well, you know, your feet are near the ground, right? You'd think that they would be abrasive - need abrasive things down there that make you want to scratch.


FLATOW: So maybe your ankles, you know, maybe that's the pleasurable part of - I'm just guessing here.

ABRAHAMS: I guess, yeah. You can - the more you think about it, the more you can start to think of all kinds of interesting experiments you could do, and people have done a lot of them. It's just nobody really seems to have done many experiments that told them anything very definite. They always end up going in a circle with just - well, the only way to put it is scratching your head about how does this stuff work.

FLATOW: Yeah. You know what they say - you're going to need a notion of calamine lotion.

ABRAHAMS: Some of them say that, yes.


FLATOW: All right, Marc. That's very interesting. Thank you. Thank you for enlightening us about scratching and itching. And now I'm squirming, so...

ABRAHAMS: Good luck, Ira.


FLATOW: Thanks a lot. March Abrahams is editor and co-founder of the Annals of Improbable Research, as well as founder and master of ceremonies for the Ig Noble Prize at - you can hear those ceremonies every Friday, the Friday after Thanksgiving, right here on SCIENCE FRIDAY, and he also writes a weekly column for the Guardian.

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