Traffic-light labelling changes way we shop for groceries

The signature red, yellow and green traffic stoplights that have been adopted in food labelling could be effective in helping consumers choose a healthier diet when grocery shopping.

Researchers at the University of Bonn have reached the conclusion that the traffic light label is more effective in helping consumers resist high-calorie foods than a purely information-based label.

For example, red symbolizes a high percentage of fat, sugar or salt, and green represents a lower percentage.

"A traffic light label probably implicitly increases the weight consumers place on healthiness in their decision," said Prof. Bernd Weber of the Center for Economics and Neuroscience (CENs) at the University of Bonn on Monday.

About 100 products, from chocolate to yogurt to ready-to-serve meals, and their nutritional information were shown to 35 adult participants while lying in the brain scanner. The participants were informed of the nutritional information by either the currently used labels with grams and percentages per portion, or in the form of traffic light labels. Then, participants had to indicate how much they were willing to pay for a particular product.

Results showed that participants were willing to pay significantly more money for products when the traffic light label was green compared to when they were presented with the same product's current nutritional information label. However, if the label was red, the willingness to pay decreased more compared to the conventional health advisory.

The reason behind this phenomenon is that a red traffic light label activated a structure in the left inferior frontal gyrus, which has been repeatedly shown to be important for self-control. Activity in this region influenced the ventromedial prefrontal cortex, a region that calculates the subjective value of a product via the reward system, leading to a decreased willingness to pay for unhealthy products.

"The traffic light label appears to enable the study participants to better resist unhealthy foods compared to a label containing the traditional information on grams and percentages of the particular ingredients," said Weber.

The study, published in the journal Obesity, is the first study that analyzes the effect that traffic light signals have on the evaluation processes in the consumer's brain when making a purchase decision, according to Weber. Endit