When kids are little, they learn red means "stop" and green means "go" by playing Red Light, Green Light. Of course, the familiar game is based on the colors of a traffic light, and most people know what the colored lights mean — even if they've never played the game.

So it makes sense to use those symbolic colors to let people know that some things are positive (green), some things are negative (red) and some things require caution (yellow).

Researchers at the Perelman School of Medicine at the University of Pennsylvania decided to test this theory by adding color-coded or numeric calorie labels to online food ordering systems, creating "traffic-light" calorie labeling. They found people ordered fewer calories per meal when there was some kind of information — either traffic light symbols alone, calorie counts alone or a combination of both. Overall people ordered 10 percent fewer calories when they had some sort of calorie information next to the menu items vs. when their was no information, reports Science Daily.

For the study, employees were able to order lunch at their company's cafeteria through an online portal. Over six weeks, 803 orders were placed by 249 participants. The traffic light labeling was more effective for participants who scored poorly on a math test, which leads to an interesting point.

In May 2017, the FDA will begin requiring calorie counts on labeling for restaurants, movie theaters, vending machine and food delivery services. Those counts may be useful for those who are better at math or those who are well educated in nutrition, including what calories are and how many the average person should consume daily. For those who aren't so good at math or have never been taught about calories, the color-coded traffic symbols are much easier to understand, so this group may be more likely to make healthier choices with the color symbols than with the numbers alone.

Researchers believe more research is needed with different menu types and a varied range of participants if practical conclusions are to be drawn from these tests.

And if the FDA is serious about better informing consumers about the food they're ordering, the agency should take into consideration the findings of this study, which shows some consumers may benefit from a system that goes beyond calorie counts. A symbolic, visual aid, alongside calorie counts, could reach more people.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.