Yesterday I attended the annual convention of the American Psychological Association (APA) in San Francisco. I was also measuring (again) the time course of omega-3 effects. The exhibits hall was full of books. I picked up three introductory psychology texts to see what they said about nutrition. None of their indexes listed nutrition; apparently they said nothing about it. None of the hundreds of books I saw was about nutrition — that is, about how to nourish the brain. Yet the APA is mainly about mental health.
It’s not just APA. At Berkeley, I’ve attended dozens of talks in the Nutrition Department. I have never seen another psych professor or grad student at any of them. Nor have I seen a nutrition professor at any Psychology Department talk. Both disciplines have Annual Review series. In last seven years, there hasn’t been a single article in the Nutrition series about behavior or cognition (aside from eating) nor a single article in the Psychology series about nutrition (aside from an article about weight control).
Sometimes interdisciplinary is hard. Cognitive science has tried to unite computer scientists with linguists and philosophers and psychologists. That’s hard because computer scientists are engineers, not scientists, and philosophers are neither. But nutrition and psychology are both experimental sciences. Nutrition is an independent variable (food), psychology a dependent variable (behavior). They naturally go together, especially if you are concerned with mental health.
Now and then someone will study how Disorder X responds to Nutritional Treatment Y — how depression responds to omega-3, for example. Better than nothing, absolutely, but not the best approach. By the time something is broken it is likely to be (a) a mess and therefore hard to measure and (b) hard to put back together. If you want to learn how a car works, should you study a car that works or a car that doesn’t work? The answer isn’t obvious, at least to cognitive psychologists, because for half a century they mainly studied how memory, perception, etc., failed. In the 1960s, Saul Sternberg taught the rest of the profession a better approach — namely, study a car that works. Sternberg made popular the kinds of experiments usually done today: reaction time experiments with easy problems that subjects almost always get right. My omega-3 research has illustrated the truth of Sternberg’s general point. I found much clearer effects of flaxseed oil on easy tasks (easy arithmetic, an easy memory task) than on a difficult task (digit span). A better way to learn how food affects our brains will be to study the effect of food on healthy brains. Such experiments will be much much easier than studying people who are depressed, children with ADD, schizophrenics, autistic children, drug addicts, and so on. I’m sure that the conclusions from healthy brains will generalize to malfunctioning brains, just as all cars — working or broken — work the same way.