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Bigger waistlines thanks to brain’s shortcut

U. PENN (US)—A cognitive shortcut, or heuristic, that causes people to ignore vital and obvious information may have played a significant role in America’s weight gain over the past 30 years.

Researchers at the University of Pennsylvania conducted a study in which subjects were asked to estimate the weight of adult women from either photographs or a live presentation by models. When estimating the body weight of women, participants disregarded or ignored the provided height information and focused solely on the width of the model, even when the provided height information was inflated as much as 10 inches.

In another study, student participants were asked to estimate the calories in one of two actual meals. Both meals contained the same foods, but one had larger portions than the other. The participants guessed no caloric differences between the two, assuming the portion sizes were culturally typical.

What ties these studies together is that missing information was literally thrust in the face of participants, but wasn’t used. The findings suggest there are situations where critical dimensions to understanding are devalued or ignored.

Penn psychologists point to the study as a novel example of the negative artifacts packaged within the evolved way the human brain processes information. The mind has evolved to develop a capacity to free up our conscious thinking for dangerous and reproductive situations.

“We have heuristics in our brain—simple mechanistic shortcuts that have evolved over hundreds of thousands of years, which free up precious space in our consciousness,” says Andrew Geier, lead author and a doctoral student in Penn’s School of Arts and Sciences.  “In these atypical instances, however, it’s the shortcut that hurts us.”

The researchers believe that the negative artifacts of the evolved mind may be directly connected with America’s obesity epidemic.

“We have evolved in a very different environment,” Geier says. “It used to be that food was scarce, and you ate what was available because you didn’t know where your next meal would come from.  That is not the case anymore. Although we have yet to prove this, we believe that the ecology of eating in the current food environment has become an example of the atypical situations demonstrated in this new article, which may be an explanation for why almost 70 percent of American adults are either overweight or obese. This represents a cognitive explanation for why America is gaining so much weight. The eating environment has morphed into an atypical scenario where our usually helpful mental mechanisms betray us.”

The studies were published in a paper in the June issue of the Journal of Experimental Psychology: Applied. The Penn Department of Psychology supported the research.

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