SCIENCE
12/17/2014 08:22 am ET Updated Dec 17, 2014

Why We Make Bad Food Decisions, Even When We Know Better

When we opt for that last donut in the office kitchen rather than eat the apple brought in from home, our brains are actually making some important micro-decisions before arriving at the final conclusion. According to new research from the California Institute of Technology, our ability to exercise self-control in our eating decisions may depend largely on how quickly our brains factor things like taste and healthfulness.

"What we wanted to find out was at what point the taste of the foods starts to become integrated into the choice process, and at what point health is integrated,"the study's lead author, graduate student Nicolette Sullivan, said in a statement.

Sullivan and her team asked 28 student participants who had been fasting for four hours to individually rate 160 foods, on a scale of -2 to 2, for their healthfulness, tastiness, and how much the participants would like to eat that food after the experiment finished. The participants were then presented with 280 random pairings of images of the same foods, and were asked to choose (by clicking the image) which food they preferred from each pair.

The researchers then analyzed the movement of the mouse's cursor, using a new technique they had created, which allowed them to evaluate down to the millisecond when taste and health information kicked in during the decision-making process. Using this technique, they were able to determine how quickly taste drove the mouse's movement, and how fast healthfulness did.

If the movement of the subject's cursor was driven by health shortly after being driven by taste, the result was that the subject chose the healthier option (say, broccoli over a donut). But if a subject considered taste immediately and then took some time before factoring in healthfulness, they were more apt to pick the donut, the researchers explained.

The researchers found, just as they hypothesized, we consider taste, which is concrete and immediately apparent, above health -- a more abstract measure. Taste information began influencing the decision-making process an average of 200 milliseconds before health did. Though for 32 percent of participants, health never influenced their decisions at all -- and each choice was based entirely on taste.

"A big factor here is how quickly you can represent and take into account different types of information when you are making choices," Antonio Rangel, a professor in the department of Neuroscience, Behavioral Biology, and Economics at CalTech, said in a statement. "People are making these choices very quickly—in a couple of seconds—so very small differences, even just a hundred milliseconds, can make an enormous difference in whether or how much health considerations ultimately influences the decision."

In a second experiment, the researchers determined that participants with less self-control factored in health information 323 milliseconds later than a group of participants with high self-control.

The researchers concluded that the faster we consider a food's health benefits, the more likely they are to exert self-control by choosing the healthier option. It seemed that choosing the less healthy option was a matter of critical thinking and education, rather than priorities.

The findings could have important implications for the way health information is presented.

"If you go to the supermarket, does it matter how big the calorie count information label is on the yogurt?" Rangel said in the statement. "More visible information may affect how quickly you compute health information. We don't know, but this study opens such possibilities."

Previous research has shown that considering a future outcome of good health and weight loss can also help people to choose health over taste when making food decisions. A 2013 study published in the journal Psychological Science found that future-thinking was effective in controlling caloric intake.

The findings were published in the journal Psychological Science.

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