The health-conscious know that they’re likely to wreak havoc on their hips if they eat too much at Thanksgiving dinner or dip too heartily into gigantic supermarket dispensers of candy. But what if they sampled just a little bit of each potato dish or just a couple pieces of each gummy color?

According to Barbara Kahn, vice dean and director of Wharton’s Undergraduate Division and Dorothy Silberberg Professor of Marketing, more choices—or the appearance of a wide variety of choices—actually make people eat more. “If there is a perception of increased variety, people eat more,” she says. “People don’t have hard and fast rules on how much to eat.”

Working with a colleague from the University of Illinois, Kahn discovered that people consume more not only when the actual variety of an assortment increases, but also when the perceived variety increases. People tend to eat more when there are three bowls of mashed potatoes on the table instead of one, or when they can choose between five different types of red gummy candy, even if the only difference is in the shape. How we consume, the researchers found, is more than just an issue of self-control.

To prove this, Kahn separated jellybeans into different assortments and then measured how groups of adults and children consumed those assortments differently. On one tray, Kahn separated six types of jellybeans by color, and on another, presented a scrambled assortment to the groups. Interestingly, people tended to eat more of the scrambled jellybeans rather than the neatly separated ones.

Kahn explains that with the perception of more variety, people think it’s okay to eat more. Also, she adds, “The more perceived variety, the more you will anticipate there’s fun.”

Kahn has spent years researching customer choices, brand loyalty and product assortments, and she says that this research has obvious implications for those trying to watch what they eat—and for those trying to market to consumers. Simply being aware that there are cues designed to make people consume more may be a step toward limiting consumption.

And on the flip side, putting this theory into practice can be beneficial for those who need to keep their weight up, or for parents of finicky eaters looking to stimulate their child’s appetite.