e same foods on both a tastiness scale (very untasty, untasty, tasty, very tasty) and a healthiness scale (very unhealthy, unhealthy, healthy, very healthy). That way, the researchers were able to associate the choices the subjects made during the brain scan with their stated perceptions of those foods' attributesshowing that a subject who chose broccoli during the "consider the healthiness" portion of the test might think of it nonetheless as untasty.
The researchers then classified the foods for each subject based on that subject's ratings: unhealthy-untasty, healthy-untasty, unhealthy-tasty, and healthy-tasty. Unsurprisingly, people chose healthy-tasty foods no matter where their attention had been directed.
Things got interesting when the researchers looked at the other three categories, however. Among their findings:
- When thinking about healthiness, subjects were less likely to eat unhealthy foods, whether or not they deemed them to be tasty, and more likely to eat healthy-untasty foods.
- Being asked to think about healthiness led subjects to say "no" to foods more often than they did when asked to make decisions naturally.
- There were no real differences between the choices made during the "consider the tastiness" and "make decisions naturally" portions of the experiment.
When the researchers turned to the fMRI results, they found that the vmPFC was, as predicted, "more responsive to the healthiness of food in the presence of health cues," says Rangel. And, as they'd seen previously, the robustness of that response was due to the influence of the dlPFCthat bastion of self-controlwhich was much quieter when the study's subjects were thinking about taste or their own personal choice than when they were asked to throw healthiness into the equation.
"This increased influence of the health signals on the vmPFC results in an overall value for the food that is based more on its health properties than is the caPage: 1 2 3 4 Related biology news :1
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