A system of gold star ratings that assesses a cereal’s nutritional value on a three-star scale has been shown to decrease purchase of unhealthier cereals in favor of those with more gold stars, a new study finds.

The study, published in the journal Food Policy, helps concretize the belief that nutrition information, when displayed prominently, can affect the type of food people buy. More generally, the increased sale of healthier cereals simply from tiny stars reflects the power of symbolic rewards. Customers chose which food to put in their bodies not according to calorie counts, fat content, or sugar levels, but rather, an abstract system of incentives.

To conduct their study, researchers from the U.S. Department of Agriculture, Food and Drug Administration (FDA), and University of Florida collected data on 134 Hannaford grocery stores scattered around the Northeast. The Maine-based chain has been running the Guiding Stars Program since 2006, and has since licensed the proprietary system to more than 1,800 stores in the U.S. and Canada. Researchers compared the 134 experimental stores with similar, non-participating stores in the surrounding area to better understand what impacts, if any, the stars were having.

"Our results suggest that point-of-sale nutrition information programs may be effective in providing easy-to-find nutrition information that is otherwise nonexistent, difficult to obtain or difficult to understand," the researchers wrote in the study.

They found sales of no-star cereals dropped 2.58 percent, while one-, two-, and three-star products saw modest gains from 0.5 percent to one percent in the first 20 months of the study.

"Although the percentages are small, if you think in terms of the actual quantities or boxes of cereal sold in the national market,” study author and FDA scientist Jordan Lin told the Associated Press, “this could have some important implications on the nation's health.”

Cereal purchases aren’t the only arena where simple incentives leave lasting impacts. Advertising and behavioral economics expert Rory Sutherland observed that in the British town of South Lanarkshire, enforcing speed limits became far less costly and loads more effective once the town switched from traditional speed cameras to speed-activated signs. If people were within the speed limit, a smiley face lit up; if they exceeded it, they saw a frown.

“The bizarre thing, which is baffling to conventional, classically trained economists,” Sutherland said in a 2009 TED Talk, “is that a weird little smiley face has a better effect on changing your behavior than the threat of 60 pounds of fines and three penalty points.”

The present system of gold star rankings has peers, as well. In the U.K., grocery stores have adopted a traffic light system, where calorie, fat, and sugar contents are all encoded in green, yellow, or red. The NuVal system, based out of Massachusetts, uses a 100-point scale to rate a food’s nutrition.

According to Julie Greene, healthy living manager at Hannaford, cereal manufacturers have been receptive to the Guiding Stars Program — reformulating their products rather than take their business elsewhere. Perhaps it reflects an acceptance of changing tides. Sugary cereals may be becoming a relic of the past, now that lean, whole grain cereals actively compete with products targeted mainly to kids.

If anything, Greene says, the new labels offer a tiny sliver of quiet in an aisle that is mostly noise.

"It can be very overwhelming,” she told the AP. “Every cereal box is a virtual billboard of health claims.”