How powerful is the placebo effect?

[drwex]

For quite some time it's been well understood that the so-called "placebo effect" (*) can have statistically significant effects on self-reported metrics such as peoples' level of sadness/happiness, confidence, and so on. Roughly speaking, the placebo effect is about as powerful as antidepressant pills in all but the most depressed people, leading to a question of whether the pills are in fact doing anything at all.

But scientists have been slow to accept (and there hasn't been much evidence for) the placebo effect making a difference in objectively measured criteria. Like, say, the size of your hips. This morning an NPR story (http://www.npr.org/templates/story/story.php?storyId=17792517) pointed me to some research published last month (NY Times story here: http://www.nytimes.com/2007/12/09/magazine/09mindfulexercise.html?ref=magazine) by Harvard psychologist Ellen Langer that may push this idea further into the mainstream.

In this study, Langer and a student talked with hotel maids about their level of exercise. Despite being in jobs that kept them physically active all day and often involved quite demanding manual labor these maids didn't see themselves as "exercising." Two-thirds said they "didn't exercise."

Langer then measured externally visible metrics of physical health: BP, waist-to-hip ratios, etc. Then they educated about half the maids on the amount of exercise they were getting simply by performing their normal daily jobs. The other half got no education.

One month later Langer re-measured the same physical metrics and found that for at least three of the metrics there was a statistically significant change. The women who were told they were exercising showed the kids of physical improvements you'd expect from a comprehensive exercise program.

Unfortunately, the study doesn't appear to be air-tight. It's quite possible that the educated group of maids did things differently; perhaps they were more mindful about things like their diet, etc. The placebo effect might not be the thing responsible for the observed changes. But it might. Even if it doesn't account for all of the change, it may well account for some. Fascinating.

Neither story tells me where the research was published, but it did lead me to discover that Professor Langer has published a couple of pop-science books on the topic, and I'm ordering those. I'll write more once I've read them.

(*) The term is accurate but some people view it as a pejorative in the sense of "it's all in your head - you're making it up." Really that's not what's meant. The effect is real and measurable. I'm not intending anything pejorative here.

Comments

[drwex]

It doesn't even have to be care - it's the being-paid-attention-to.

[chienne-folle.livejournal.com]

One thing I find interesting is that a lot of different animals seem to thrive when given human attention. I can see where HUMANS would have evolved to do better with human attention, but parrots? elephants? other non-domesticated animals? Why do they enjoy human attention?

[agentotter.livejournal.com]

Well, I think there you're getting into a whole other issue of what the animal's other options are. Your for-instance species, in particular, are very social animals, especially animals like elephants whose whole existence is so tied into family bonds, and who by virtue of their circumstances have turned to human affection as the only affection available. (Either that or we aren't separating the animal's perception of the human's attention from the human's perception of the animal's reaction. For instance: say I have a horse named Sparky. I go out to the paddock to visit Sparky, and he comes running to meet me and is clearly excited to see me. I think that this means he likes me, but I'm utterly failing to notice that Sparky's approach and posture indicate that his demand for affection is a display of dominance, and my giving him what he wants is my indication of submission. So is Sparky thriving on human attention, or has Sparky come running to see me because he's frustrated by his lack of exercise and disinterested pasture-mates, and he's overjoyed to see me because I'm giving him the opportunity to be dominant over someone?)

And I think it's also worth noting that the animals you mentioned specifically, elephants and parrots, are also two of the ones who suffer most obviously from mental disorders in captivity, from obsessive and compulsive behaviors to self-destructive activities and violence against people. So are they receptive to human attention because they want it, or are they seeking it out out of frustration stemming from being out of their natural environment, away from their social groups, etc.? You're asking an interesting question but it seems like there's a lot of assumptions inherent in it... before exploring for an answer I'd love to see some evidence that any non-domesticated animal (or any animal at all, for that matter) as a species derives specific benefit from human attention/affection, and not just attention in general from any other being at all. Have you seen any studies on the subject? I'd be really interested to read them.

On a sort of similar topic, there's an excellent book about how plants have evolved to be pleasing to human beings... it's called The Botany of Desire. You should check it out if you haven't read it, I think you'd find it really interesting. It centers on the concept that while we think we've selectively bred certain plant species to be pleasing to us, by the same token the plants have been evolving to make themselves attractive to us, the same way they make themselves attractive to bees, in order to more effectively reproduce themselves... so who's using who? It's an interesting topic and a really enjoyable book.