Friday, December 2, 2011

Why so much fitness and parenting advice is bullshit

Et tu, Psychology Today? And you, Dr. Michael J. Breus? What’s your excuse, Thomas Friedman?

You never have to look far to find flagrant violations of the “Correlation does not imply causation” law. They abound in newspapers, magazines, TV programs, parenting and diet books—anywhere, basically, that covers topics like parenting or fitness, and thus relies heavily on behavioral research. In the past month, you could find examples of the problem, among other places, on the website of the country’s leading popular psychology monthly, in a piece by the triple-Pulitzer-winning New York Times columnist, and in a psychologist’s column on Huffington Post.

As many of you may recall from your old science and psychology courses (or from a Brain, Child piece I wrote last year), just because two things are correlated doesn’t mean that one of them caused the other. For example, if there’s a correlation between A and B—more of A tends to go hand in hand with more of B—that’s no proof that A caused B. It might have. Or maybe B caused A, or some combination of the two, or a third factor, C, caused both.

In a Psychology Today blog post titled “Parents: Your Words Matter,” University of Chicago psychology professor Sian Beilock writes about a correlation between the way parents talk to their preschool children and the children’s later problem-solving skills. Researcher Susan Levine, Beilock reports, found that the more parents talked about spatial characteristics of objects—using words like “big, tall, circle, curvy, edge”—the better the child performs, years later, on spatial problems.

“What Dr. Levine and her colleagues found was that children's spatial abilities are in, large part, driven by what their parents say,” Beilock writes.

If that’s what Dr. Levine and her colleagues really found, there’s no evidence of it in Beilock’s post, nor in the abstract of Levine’s article in Developmental Science. Based on what they present, it could just as easily go the other way around.

Now, I’m not going to argue that parents words don’t matter (though in research I’ve conducted in my own household, I found little correlation between parental instructions to take one’s dirty dishes into the kitchen and the likelihood that one’s dirty dishes will actually be taken into the kitchen). It may seem logical that a child who’s always hearing her parents talk about objects' sizes and shapes might be more attuned to those qualities and, thus, better at solving problems involving those concepts.

That might make intuitive sense, but intuition isn’t proof—another lesson from those college psychology courses. Besides, it’s just as intuitively logical that parents who are good at spatial problems are more likely to perceive the world in spatial terms and (unconsciously, perhaps) pepper their language with spatial words. And that their children tend to inherit those skills and later prove, unsurprisingly, to be good at spatial stuff, too.

One big moral of this story is that simple correlations between parental actions and children’s behavior rarely proves cause and effect if the parents and children are biologically related. In most stuations, it’s too difficult to rule out the possibility that genes, rather than parenting, are the cause. 

Thomas Friedman forgets that, too. He writes about a study in which 15-year-olds whose parents read to them when they were little scored higher on a test than kids whose parents didn’t. From this, Friedman concludes:
We need better parents. Parents more focused on their children’s education can also make a huge difference in a student’s achievement.

Spot the correlation/causation error here? Again, it's a problem of ignoring possible genetic influence. What kind of parents read books to their kids? Probably those who like to read themselves. What kind of people like to read? Usually people who are good at reading. What kind of parents involve themselves in their child’s education? Most likely parents who did well in school themselves.

So it’s no big leap to imagine that children who are read to also inherited their parents' reading skills and academic achievement. Yet neither Friedman nor the researchers seem to have considered that possibility. But hey, even if their conclusion were 100 percent scientifically sound, they still would hardly justify this comment, quoted by Friedman, from the guy who oversees the testing:

[J]ust asking your child how was their school day and showing genuine interest in the learning that they are doing can have the same impact as hours of private tutoring.

First, judging from the monosyllabic grunts I usually get in answer to that question, it seems doubtful. Anyway, how would he know this? I’m going to step out on a limb and guess that there probably aren't many parents alive who purchase “hours of private tutoring” for their children yet don't bother to ask how school is going. So who would be the control group here?

Finally, in his rhymingly titled Huffington Post piece, “Sleeping Late, Eating Late, Leads to Gaining Weight,” Michael J. Breus similarly jumps to a conclusion, based on a correlation between sleep patterns and weight gain.

A message to night owls: There's news that your bedtime -- and those late-night snacks -- may be preventing you from dropping those stubborn extra pounds.

 Again, it’s not hard to think of another explanation for this correlation: That people who like to stay up late are often also people who like to eat a lot. As a card-carrying member of both groups, I can vouch for this. But Breus, a.k.a. “The Sleep Doctor,” doesn’t even consider that possibility. Wonder if this could have anything to do with the topic of his recent book, The Sleep Doctor's Diet Plan: Lose Weight through Better Sleep.

Even if those writers and researchers are leaping to conclusions, you might ask, where’s the harm? Why wouldn't you want to ask about your kid's school day, whether it got him better test scores or not? (Do you ask about your partner's work day, even if you don't think it will get him or her a raise?) Besides, if there’s any chance, however slight, that it would improve their school performance, why not go for it? Asking the question is pretty easy.

The spatial language situation is a bit more difficult. You might be willing to stop and think about every word you say to your child and deliberately insert spatial terms into the mix. (Although what if by doing that you’re squelching some other form of communication that might be equally important? I used to play word games with my then-preschool kids. On the day when I asked one to name the opposite of “short” and he came back with both “long” and “tall,” I knew he would be good in language classes, and voila, he is. Yet I can't say his language skills are the result of playing word games; very likely, he and I both liked playing word games because we’re both good at language.)

But the most damaging result of all of this misinterpretation and misinformation is guilt. It's the guilt you might feel if you take Friedman seriously when he proclaims, “We need better parents.”

Don’t most of us—at least, those of us who comprise the audience for these articles, i.e., people interested in figuring out how to be better parents—already do plenty of fretting about what we’re doing wrong? Must we really be told, once again, that we’re never good enough?


  1. Your post reminds me of another recently reported study: if you take multi-vitamins, you're more likely to die young. But the study didn't take into account that many people taking multi-vitamins and other supplements might be doing so because they are fighting some chronic disease! People who feel great all the time might be much less likely to even think about taking a multi-vitamin. Really, if you're going to do a study like that, but not control for such obvious factors, you're wasting your research time!

  2. Good one, Cassi! I've fallen for that one, myself; I rarely take multivitamins because I keep reading they're bad for you. And controlling for current health conditions, even breaking them down by specific ailments, wouldn't seem to be all that difficult.

  3. Hm. I wonder also if many of the most frequent takers of multi-vitamins neglect other aspects of health because they figure the vitamins cover a lot of it? Who knows. My mother, for example, doesn't exercise or eat right, but takes loads of vitamins.

    I wish more people would point these things out. Superfreakonomics had a section about the misconception that kids whose parents read to them daily end up doing better academically. They compared the idea with their own research, which showed that it's actually just having books in the house that makes the difference.

    But the way they described it seemed to me more correlation than causation, for many of the reasons mentioned in your post. I would guess that people who have books--particularly a lot of books--in the house would be people who read a lot. And whether or not you read to your kids, your kids will see you reading and often want to imitate you. And on the other hand, if you read a lot you're likely to be intellectually curious and your kids might inherit that. I'd guess.

    Anyway, none of these studies end up describing the effects or values they're trying to quantify, which to me seems like a greater problem. In the Superfreakonomics one, the effect they measured was on standardized test scores, which leads any half-brainy person to question whether high test scores is what you're trying to accomplish when you're raising your kids. What, exactly, is meant by 'achievement'?

    I particularly liked your point about the spatial problems. I am very weak in spatial relations, but my husband is an engineer and physicist. Our son gets a good 90% of parenting time from me, but I can see my husband's genetics come out when we're playing with wooden train tracks. At 4 years old, my son can visualize complicated layouts that I'd never come up with, and I can assure you it doesn't come from me using spatially related words!

  4. When I read something like, "We need better parents," I think I'd like to start with those who abuse their kids, leave preschoolers alone for hours, don't bother to feed them and say horrible, soul-sucking things to their kids. I have some parenting regrets (and some legitimate shortcomings), but I would be happy if all parents were only as good as I was.

  5. Also, I'm all for doing stuff that *might* have positive results, even for myself. For example, I like to exercise my brain, like looking out for things of a certain color, doing "associative writing" exercises, playing brain/word games, etc. But I don't necessarily believe it will have much of an effect. It just feels productive and rewarding, and makes me think maybe it keeps me sharper.

    But to do that sort of thing as rote to train a child seems kind of military, especially considering how many activities one *could* do that have been touted as turning them into more brainy kids.