Eric Mead's TED talk on the magic of the placebo has spawned some interesting comments. The site's top 3 adjectives to describe it are "Confusing", "Funny", "OK". As I write this, there are still very few comments and every one is a variation on "Huh. That was interesting, but I'm not sure what he's trying to say."
Here's my take on it, written in full ignorance of any comments that came along later that explain Mead's talk.
First, a quick summary. Mead comes out, shows the audience a simple magic trick where he makes it look like he's got a knife stuck to his hand. In reality, as he shows us, he's holding it up with a finger. But people's brains don't notice that not all of his fingers are visible and accounted for; they only see the knife hanging there like magic.
Then he talks a bit about placebos and what he finds fascinating about them. A little blue pill with writing on it is more effective than a plain white pill, even if they're both placebos. And a placebo injection is most effective of all.
So then he repeats his knife trick, with a twist. Instead of a knife, he produces a long needle, which he purportedly sticks through the skin of his forearm. He leaves it hanging there, and removes his other hand, showing that he couldn't be using the same trick that he used for the knife.
Then he shows us the alleged wound, and it looks like he's really pushed the needle through his skin and a bit of flesh, leaving it firmly attached to his arm. (The audience squirms in discomfort.) Then he goes so far as to wriggle it around, producing some realistic-looking "blood." (Several audience members cover their eyes and peek out from between fingers.)
And then -- he doesn't remove the needle, he doesn't show us how it's done like he did with the knife, he just leaves us to think about his message.
Here's what I think his message was:
Why are injections more effective placebos than pills? Because we human beings naturally respond much more strongly to needles and blood than to something innocuous like swallowing a pill. This is a reaction that occurs very deep in our unconscious minds.
Mead demonstrates this through his two magic tricks. The audience applauds politely when he makes the knife stick to his skin. But if he'd ended there, even if he hadn't explained how he did it, it probably wouldn't have stuck in their minds for very long. So he got something to stick to his wrist when it ought to have fallen to the floor. Big whoop. Everybody knows an 8-year-old who can do that.
Compare the audience's reaction when he brings out the needle. Even before we see the "wound", when for all we know it's being held there with his finger, there's already a strong "squick" reaction. Needles and the idea of piercing flesh gets people's hindbrains involved.
And when Mead shows us the "wound" dripping "blood" and never lets on how he did it, he insures that the people in the audience won't forget his performance for a long, long time. (I won't either. I mean, I know it's all a trick, but I thought he sounded somewhat dazed at the very end. Which is just what you'd expect to hear if he really had pierced his arm through with a needle...)
That's his lesson. He doesn't just tell us that our unconscious reacts more strongly when these visceral feelings excite our hindbrains. He tells us and shows us.