Anyone who has ever run fast from the smell of a tuna fish sandwich might be surprised by the results of a new study on food choices. The research, from the International School for Advanced Studies (SISSA) in Trieste, has actually identified sight as the main sense we use when deciding what to eat.

Researchers discovered that human brains are wired to choose certain colors, specifically red food over green cuisine, making an apple a much likelier candidate than a green salad, or the tuna's mystery gray. In this case, red means "go," and green means "stop," the researchers noted in a press release.

To reach these conclusions, study participants judged food's appeal based solely on sight. Researchers found that red foods, like meat, were generally perceived as higher in calories, while the opposite was true for greens like vegetables.

"This is also true for processed, or cooked foods, where color loses its effectiveness as an indicator of calories,” study author Giulio Pergola explained in a press release from the SISSA.

The authors suggest that our color preferences may be a throwback to evolutionary forces that helped us select foods in nature that were edible and nutritious.

"According to some theories, our visual system evolved to easily identify particularly nutritious berries, fruits and vegetables from jungle foliage," study coordinator Raffaella Rumiati said in the release.

“We are visual animals, unlike others, dogs, for example, who depend on their sense of smell. We are particularly efficient at distinguishing red from green,” she continued. “It is mainly the color of food that guides us, and our experiments show how. To date, only a few studies have been focused on the topic.”

In the future, these findings could have potential impacts on food marketing and eating disorder treatments.

Source: Forni F, Pergola G, Rumiati RI. Food color is in the eye of the beholder: the role of human trichromatic vision in food evaluation. Scientific Reports. 2016.

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