Experimental Design in Action

Behind the University of California's rather work-a-day exterior in San Francisco, an almost fantastic investigation of the psychology of pain goes on. Howard Fields wanted to know how pain was relieved by a placebo, a dose of some inactive substance-- an imaginary cure.

The university dental school could offer patients who were guaranteed to suffer pain after wisdom tooth extraction.

OK?

OK, Fred. Couple more.

When the anaesthetic wears off, Fred, the volunteer patient, assesses his pain.

Pain is increasing. [INAUDIBLE]

The experiment is double blind. Howard Fields allots treatment only to a number.

Patient 7250, placebo Naloxone.

This patient, number 7250, will receive a placebo, a harmless saline solution, instead of a painkiller. Changing the label ensures the bottle can only be identified by number.

All righty. OK. I'm going to give you your first medication now, so--

OK.

[INAUDIBLE]

Fred gets his first injection. Unknown to him or the doctor, it is the placebo. In one out of three cases, it will reduce the pain. And so the first hurdle is, does a placebo work for Fred?

[TIMER RINGING]

Time passes.

OK, Fred. We've got a couple more forms for you to fill out. There you go. How are you feeling now?

The pain seems to be going down some.

The pain is less. The placebo is working.

Pain is decreased.

Number one. Number two is Naloxone.

The second injection will be Naloxone, which would stop the effect of a painkiller, if it were given, by binding to the morphine receptor sites. The big question is, would it stop the effect of the placebo? If so, presumably enkephalins, or endorphins, are involved in the placebo effect.

The unfortunate Fred gets his Naloxone, which would increase his pain if the first injection had been morphine. Again, neither he nor the doctor knows it's Naloxone.

This will help take care of the pain that you're feeling right now.

In fact, 1 in 10 of the second injections is morphine to [? relieve ?] the doctor's objection to causing pain, like a blank round issued to a firing squad.

[TIMER RINGING]

OK, Fred. I've got a couple more for you. They're endless.

Is the pain better or worse? Worse. So the imaginary cure is producing real chemicals.