placebo effect

On the Placebo Effect and Dieting

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There’s nothing spectacular in this Wall Street Journal piece on the magic of placebos, but I thought this was an interesting paragraph concerning dieting:

Another study, published earlier this year in the journal Health Psychology, shows how mind-set can affect an individual’s appetite and production of a gut peptide called ghrelin (GREL-in), which is involved in the feeling of satisfaction after eating. Ghrelin levels are supposed to rise when the body needs food and fall proportionally as calories are consumed, telling the brain the body is no longer hungry and doesn’t need to search out more food.

Yet the data show ghrelin levels depended on how many calories participants were told they were consuming, not how many they actually consumed. When told a milkshake they were about to drink had 620 calories and was “indulgent,” the participants’ ghrelin levels fell more—the brain perceived it was satisfied more quickly—than when they were told the shake had 120 calories and was “sensible.”

Hence, the reasoning that the notion of dieting is altering our mindset, and we end up consuming more (since we know we aren’t getting enough food).

This reminds me of how using a bigger fork can help you eat less. Also, smaller plates and contrasting colors can dampen your appetite:

[Participants] were served different-sized plates filled with food. Those who were given larger plates filled their plates with more food than those with smaller plates. Those who were served food on tables with a higher color contrast between the plates and the tablecloth also ate more than those who were served the same amount of food without a noticeable contrast.

The problem with all of these studies is that by becoming conscious of how you’re trying to beat the system, you begin to override the placebo effect. In other words, if you made an effort to eat with a larger fork and using smaller plates, you can’t trick your brain for long: eventually, you’ll just compensate by eating more food (or more frequently). Show me a study where dieting is proved to conclusively work, and I’ll show you a millionaire.

The Placebo Effect and the Self Management System

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Nicholas Humphrey, a theoretical psychologist and author of A History of the Mind, has a fascinating post on the placebo effect and the relation between the health management system and what he dubs the self-management system. The basic premise is this: we know the placebo effect has a way of making people feel better in the medicinal sense. But what if we could prime people to change their behavior, attitudes, and personality?

It’s been a tremendous surprise for experimental psychology and social psychology, because until now it’s been widely assumed that people’s characters are in fact pretty much fixed. People don’t blow with the wind, they don’t become a different kind of person depending on local and apparently irrelevant cues . . . But after all, it seems they do.

So if we don’t discount the placebo effect in medicine, how does it fit in with the rest of the argument?

Placebos work because they suggest to people that the picture is rosier than it really is. Just like the artificial summer light cycle for the hamster, placebos give people fake information that it’s safe to cure them. Whereupon they do just that.

This suggests we should see the placebo effect as part of a much larger picture of homeostasis and bodily self-control. But now I’m ready to expand on this much further still. If this is the way humans and animals manage their physical health, there must surely be a similar story to be told about mental health. And if mental health, then—at least with humans—it should apply to personality and character as well. So I’ve come round to the idea that humans have in fact evolved a full-blown self management system, with the job of managing all their psychological resources put together, so as to optimise the persona they present to the world.

You may ask: why should the self need any such “economic managing”? Are there really aspects of the self that should be kept in reserve? Do psychological traits have costs as well as benefits? But I’d say it’s easy to see how it is so. Emotions such as anxiety, anger, joy will be counterproductive if they are not appropriately graded. Personality traits—assertiveness, neuroticism, and friendliness—have both down- and up-sides. Sexual attractiveness carries obvious risks. Pride comes before a fall. Even high intelligence can be a disadvantage (we can be “too clever by half”, as they say). What’s more—and this may be the area where economic management is most relevant of all— as people go through life they build up social psychological capital of various kinds that they need to husband carefully. Reputation is precious, love should not be wasted indiscriminately, secrets have to be guarded, favors must be returned.

So, I think humans must have come under strong selection pressure in the course of evolution to get these calculations right. Our ancestors needed to develop a system for managing the face they present to the world: how they came across to other people, when to flirt, when to hold back, when to be generous, when to be mean, when to fall in love, when to reject, when to reciprocate, when to punish, when to take the lead, when to retire, and so on. . . All these aspects had to be very carefully balanced if they were going to maximize their chances of success in the social world. 

Fortunately our ancestors already had a template for doing these calculations, namely the pre-existing health system. In fact I believe the self management system evolved on the back of the health system. But this new system goes much further than the older one: it’s job is to read the local signs and signs and forecast the psychological weather we are heading into, enabling us to prejudge what we can get away with, what’s politic, what’s expected of us. Not surprisingly, it’s turned out to be a very complex system. That’s why psychologists working on priming are discovering so many cues, which are relevant to it. For there are of course so many things that are relevant to managing our personal lives and coming across in the most effective and self-promoting ways we can.

You should read the entire piece here.