The Year in Science: Psychology

Why stupid people die young, and a diet based on memory alteration.

Sunday, January 08, 2006

At Last: We Find Out Why Stupid People Usually Die Young

In 2001 researchers in Great Britain were surprised to discover that people with low IQs live shorter lives. But a more startling finding came this year with a report that reaction time proved an even stronger predictor of life span than IQ.

Ian Deary, a psychologist at the University of Edinburgh, and Geoff Der, a statistician at the MRC Social and Public Health Sciences Unit in Glasgow, suspected that higher IQ might lead to healthier habits like not smoking or healthier environments like safer office jobs. So they looked at data on 898 people first tested at about age 56, and then tracked their survival until age 70. They found that the link between IQ and mortality held strong even after adjusting for education, occupation, social class, and smoking.

But the group had also taken button-pressing reaction-time tests, which measure how quickly and accurately a person repeatedly makes a simple decision. Deary and Der wanted to find out whether there was still a relationship between mental ability and survival once a person's reaction time was taken into account. "And there wasn't," Deary says. The upshot: "We could explain the association between mental ability and survival with reaction time." In this study, the reaction times tested in subjects at age 56 appeared to have about as strong a link to chances of survival over the next 14 years as did being a smoker.

Why is still uncertain. One possibility is that reaction time slows because an undetected disease has begun to compromise performance. Another hypothesis is that the differences result from more fundamental, lifelong variations in the speed at which people process information. Both factors could be at work. For clues, Deary hopes to track a younger sample over several years.

The study has sparked interest in what its authors call "cognitive epidemiology," the study of associations between mental ability tests and health outcomes. "One of the indicators of whether mental ability tests are useful is whether they predict things about real life," Deary says, and these findings suggest they do.  —Marina Krakovsky 

Can Memory Manipulation Change The Way You Eat?

A study published in September suggests there is a surprising way to get people to avoid unhealthy foods: Alter their memories. Cognitive scientist Elizabeth Loftus of the University of California at Irvine and her colleagues asked volunteers to fill out lengthy questionnaires on their personalities and food experiences. "One week later," Loftus says, "we told subjects we'd fed their data into our smart computer and it spun out a profile of their early childhood experiences." Some profiles included one key additional detail: "You got sick after eating strawberry ice cream." The researchers then converted this plausible detail into a manufactured memory through leading questions—Who were you with? How did you feel? By the end of the study, up to 41 percent of those given a false memory believed strawberry ice cream once made them sick, and many said they'd avoid eating it.

When Loftus published her findings, she started getting calls from people begging her to make them remember hating chocolate or French fries. Unfortunately, it's not that easy. False memories appear to work only for foods you don't eat on a regular basis—if you had one awful experience with chocolate as a child, you've probably had enough positive ones since to override it. But most important, it is likely that false memories can be implanted only in people who are unaware of the mental manipulation. And lying to a patient is unethical, even if a doctor believes it's for the patient's benefit.

Loftus says there's nothing to stop parents from trying it with their obese children.  "I say,  wake up—parents have been lying about Santa Claus and the Tooth Fairy for years, and nobody seems to mind. If they can prevent diabetes and obesity and all the problems that come with that, you might think that's a more moral lie. Decide that for yourself."  —Rebecca Skloot

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