Myths About Danger Of Fatty Foods Due To "Cascade" Of Erroneous Thinking And Repetition Of Errant Claims

I think this guy Gary Taubes wrote "What If We've Been Wrong All Along?," a NYT magazine piece debunking the anti-fat hysteria in medicine and the media (which wound up putting me on the Atkins diet a month or so later).

He has a whole book about the topic now. But I don't consider that terribly interesting since I already believe him. More interesting to me is John Tierney's description of the "cascade" effect, where scientists -- Olympic-level skeptics and painstaking verifiers of claims, supposedly -- just go along with the popular mode of thought.

Does any of this sound like it might be going on in climatology circles?

In 1988, the surgeon general, C. Everett Koop, proclaimed ice cream to a be public-health menace right up there with cigarettes. Alluding to his office’s famous 1964 report on the perils of smoking, Dr. Koop announced that the American diet was a problem of “comparable” magnitude, chiefly because of the high-fat foods that were causing coronary heart disease and other deadly ailments.

He introduced his report with these words: “The depth of the science base underlying its findings is even more impressive than that for tobacco and health in 1964.”

That was a ludicrous statement, as Gary Taubes demonstrates in his new book meticulously debunking diet myths, “Good Calories, Bad Calories” (Knopf, 2007). The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly. The evidence against Häagen-Dazs was nothing like the evidence against Marlboros.

It may seem bizarre that a surgeon general could go so wrong. After all, wasn’t it his job to express the scientific consensus? But that was the problem. Dr. Koop was expressing the consensus. He, like the architects of the federal “food pyramid” telling Americans what to eat, went wrong by listening to everyone else. He was caught in what social scientists call a cascade.

We like to think that people improve their judgment by putting their minds together, and sometimes they do. The studio audience at “Who Wants to Be a Millionaire” usually votes for the right answer. But suppose, instead of the audience members voting silently in unison, they voted out loud one after another. And suppose the first person gets it wrong.

If the second person isn’t sure of the answer, he’s liable to go along with the first person’s guess. By then, even if the third person suspects another answer is right, she’s more liable to go along just because she assumes the first two together know more than she does. Thus begins an “informational cascade” as one person after another assumes that the rest can’t all be wrong.

Because of this effect, groups are surprisingly prone to reach mistaken conclusions even when most of the people started out knowing better, according to the economists Sushil Bikhchandani, David Hirshleifer and Ivo Welch. If, say, 60 percent of a group’s members have been given information pointing them to the right answer (while the rest have information pointing to the wrong answer), there is still about a one-in-three chance that the group will cascade to a mistaken consensus.

Cascades are especially common in medicine as doctors take their cues from others, leading them to overdiagnose some faddish ailments (called bandwagon diseases) and overprescribe certain treatments (like the tonsillectomies once popular for children). Unable to keep up with the volume of research, doctors look for guidance from an expert — or at least someone who sounds confident.

A bit more on faddish scientific cascades at Tierny Lab. Alas, it's all about diet again; he doesn't make the leap to global warming faddism.

Related: People eat more calories in restaurants they think are "healthy," because they undercount calories and often order extra sides they wouldn't in an "unhealthy" restaurant.

posted by Ace at 03:35 PM

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