Could Traffic Lights Curb Meat Consumption?

Traditionally, policymakers have tried to change peoples’ food habits trough restricting access to or limiting the marketing of certain foods, providing people with information and education, or economic incentives to change food habits.  However, such interventions have unclear effects on people’s actual food choices. According to behavioral economics, many daily decisions are fast, intuitive and occur outside cognitive awareness. Changing the food environment and presentation of food options may therefore influence customers’ food choices without removing options or changing economic incentives. 

In the past, scientists have examined labeling in the context of calorie counting. Two reviews argued that simple traffic-light labels, or labels that simply identify the best option, attract more attention than detailed labels. In those studies, researchers argued that traffic-light labels work well because consumers intuitively grasp the implicit messages of the relative colors and can compare options within the same category. 

Another stream of research has studied how introducing a third option influences preferences, also called the compromise effect. The compromise implies that the middle option becomes more attractive or popular when a smaller or larger option is introduced, compared to when only the two extremes are available. In a calorie labeling study, customers avoided the largest and smallest caloric items and chose the items in-between. In another study, the middle size became more likely to be purchased when a larger and a smaller drink size option was added to the range of choices. 

Therefore, it’s hypothesized that traffic light labels could lead to an increase in purchases of the middle option. In this study, researchers thought that single positive signs such as a green label could communicate that an option is positive, while a red sign can imply a negative warning. An additional major gap in the literature is if simple food labels work overtime in settings where customers are exposed to labels multiple times. Some have argued that customers develop “fatigue” for labels when exposed to them multiple times, and that labels stop working after time and repeated exposure. For these reasons, the researchers say that it’s important to determine the impact of eco-labels on real food purchases over time.

In this study, three different labeling systems were tested on warm dishes in the largest cafeteria at the University of Oslo. The first system was traffic-light labels with three symbols (red, yellow and green), the second system was a single-green label that only labeled the most environmentally-friendly dishes, and the third system was a single-red label that only labeled the least environmentally-friendly option. 

For the single-green labeling format, only the vegetarian dish was labeled with the “Low CO₂” sign. In contrast, the single-red labeling format exclusively marked the meat dish with a “High CO₂” label. Posters were placed around the cafeteria, explaining the labeling systems and the climate impact of different food categories, but customers were not forced to read them. Outcome was measured by the sales share of meat, fish and vegetarian dishes. The intervention period was separated in two; the first 20 days (period 1) took place before Christmas holidays, and the next set of 22 days (period 2) took place after Christmas holidays.

The results were promising: the traffic-light labels reduced sales of dishes with land animals by 9% in period 1 but not in period 2. Overall sales share of fish or vegetarian dishes were not impacted. Single-green and single-red labeling had no effect on sales share of meat, fish or vegetarian dishes in period 1, nor in period 2.

Based on these results, the researchers concluded that a traffic-light label, in combination with information – in this case, posters – can reduce the consumption of land animals, at least in the short-term. The results suggest that the traffic-lights led to a switch from red choices to the yellow middle option: sales of the green-labeled vegetarian dish did not increase as much as sales of the middle yellow labeled fish dish. 

We can interpret it as support for the compromise effect, meaning that the traffic-light labeling led to an increase of the middle option, and not to a switch to the more “extreme” green option. If that is so, we assume that offering a plant-based option as the middle option (such as tofu or as opposed to two extremes: meat on the one hand and vegetables on the other hand) should have the same effect, swaying potential animal food consumers to the plant-based middle option. 

Another interpretation of the same result might be that meat-hungry consumers prefer fish proteins to pure vegetarian meals, and that the meat and fish dishes were considered more similar to each other than a vegetarian dish. If that is the case, we can assume that people won’t switch to the plant-based middle option and that we’ll need a different intervention. 

Customers seemed to react favorably to the traffic-light label when first introduced, but their eco-friendly behavior declined over time and almost returned to the control period behavior after some months during period 2. These results could be evidence for customers developing “fatigue” for labels, and that the effect of the ecolabels in this study was only relatively short-lived. A notable strength of the study is that the researchers measured changes in actual purchase choices, rather than relying on self-reported behavior. In summary, as meat consumption has a significant negative environmental footprint, and more traditional policy interventions do not fully seem to capture peoples’ motivations when choosing what to eat, behavioral economics interventions can be a relevant future area of research and action.