Color lets you feel the answer in the time it takes to reach.
In the brief, almost unconscious moment a shopper reaches for a product, color may carry more moral weight than any written warning. Researchers at Göttingen University have found that the Nutri-Score nutrition label — a five-tier system rating food from green to red — guides purchasing decisions far more effectively when rendered in full color than in grayscale, suggesting that the design of information is inseparable from its power to change behavior. Yet the study also surfaces a quieter paradox: the red warning, the signal meant to protect, failed to deter — revealing that human choice is shaped not only by what we see, but by what we are willing to act upon.
- Eye-tracking data from 199 German shoppers revealed that colorful Nutri-Score labels commanded attention longer and more reliably than monochrome versions, making the case that visual design is a public health variable.
- Green and yellow ratings translated directly into purchases — shoppers who noticed them were significantly more likely to place those products in their baskets, showing that positive signals can nudge behavior in real time.
- The red 'E' warning, however, proved ineffective: even repeated glances at the unhealthy rating did not stop shoppers from buying the product, exposing the limits of cautionary labeling against habit, price, and preference.
- Researchers are now pressing policymakers to mandate full-color Nutri-Score placement on both front packaging and shelf price tags, arguing that the moment of decision — at the price tag — is where the label must land.
- Because adoption of the Nutri-Score remains voluntary across the EU, the labeling landscape is fragmented, and the study's authors warn that inconsistency undermines the system's potential to shift population-level purchasing habits.
Walk into a German supermarket and the choice of what to reach for happens in seconds. According to researchers at Göttingen University, that split-second decision is shaped, in part, by something as elemental as color. A new eye-tracking study found that the Nutri-Score labeling system — which rates food on a five-tier scale from green (A, healthiest) to red (E, least healthy) — works significantly better when displayed in full color rather than grayscale.
The research team, a collaboration across four German universities and food science institutes, recruited 199 shoppers and placed them in a simulated supermarket. Participants were divided into groups exposed to different labeling conditions: colorful labels on both packaging and shelf price tags, grayscale versions in the same locations, a single color label on packaging only, or no label at all. Eye-tracking technology recorded where attention fell and how long it lingered.
The full-color labels won decisively. They attracted more frequent and sustained attention, and — crucially — when shoppers noticed a bright green A or yellow C rating, they were meaningfully more likely to purchase that product. The visual signal registered and persuaded.
But the data held a troubling counterpoint. The red E label, designed to warn consumers away from the least healthy options, failed to deter purchases even when shoppers looked at it repeatedly. Whatever the red rating communicated, it was not enough to override price, habit, or brand loyalty.
Lead researcher Dr. Clara Mehlhose noted that the Nutri-Score's value lies in offering intuitive guidance at the moment of purchase — and that color is not decorative but functional, allowing a label to be understood in a fraction of a second. The study's broader implication is a policy one: for the Nutri-Score to fulfill its public health purpose, it should be mandated in color and placed not only on packaging but on the shelf price tags where final decisions are made. As long as adoption remains voluntary and inconsistent across the EU, the system's potential to meaningfully shift what ends up in shopping carts will remain only partially realized.
Walk into a German supermarket and you're faced with a choice that happens in seconds: which product do you reach for? The answer, according to researchers at Göttingen University, depends partly on something as simple as color. A new study tracking how shoppers' eyes move through the aisles found that the Nutri-Score labeling system—a five-tier nutritional rating that runs from green (A, the healthiest) through yellow and orange to red (E, the least healthy)—works best when it's displayed in full color rather than in grayscale.
The Nutri-Score itself is not new. It's an optional labeling scheme used across the European Union, adopted by major retailers and food companies in countries like Germany and the Netherlands. The label distills a product's nutritional profile into a single, easy-to-read rating. But how visible is it, really? And does it actually change what people buy? Those were the questions that drove the research collaboration between Göttingen University, Osnabrück University of Applied Sciences, the German Institute of Food Technology, and Giessen University.
The team recruited 199 shoppers in Germany and placed them in a simulated supermarket environment. They divided participants into four groups, each seeing a different labeling setup: colorful Nutri-Score labels on both the front of packages and on shelf price tags; grayscale versions in the same locations; a single colorful label on the front package only (the current standard in many stores); or no label at all. Eye-tracking technology recorded exactly where each shopper looked and how long their gaze lingered before they made their selection.
The results were striking. The full-color traffic-light labels—particularly when displayed on price tags alongside the front-of-package marking—captured attention far more effectively than their grayscale counterparts. Shoppers' eyes landed on these labels more frequently and stayed longer. More importantly, when people looked at the bright green A or the yellow C ratings, they were significantly more likely to actually put that product in their basket. The visual signal seemed to register, to persuade.
But there was a troubling finding buried in the data. The red E label, meant to warn consumers away from the least healthy products, failed to do its job. Even when shoppers noticed the red rating and looked at it repeatedly, they still bought the product. The warning didn't stick. The color that should have stopped them cold apparently didn't carry enough weight to override other factors—price, habit, brand loyalty, taste preference.
Dr. Clara Mehlhose, who led the study, emphasized that the Nutri-Score's purpose is to offer quick, intuitive guidance in the moment of purchase. "It is crucial that shoppers can recognise and understand the information at a glance," she said. The research suggests that color is not decorative—it's functional. A multicolored label can be grasped in a fraction of a second. Grayscale requires more cognitive effort, and in the busy environment of a supermarket, that difference matters.
The findings point toward a policy implication that researchers and public health advocates are now pushing: if the Nutri-Score is going to work as a tool for steering people toward healthier choices, it needs to be displayed in color, and it needs to be visible not just on the package itself but on the price tag where shoppers make their final decision. The more consistently companies use the colored system, the easier comparison shopping becomes. Right now, adoption is voluntary, which means the labeling landscape remains fragmented. Some stores use it, some don't. Some use color, some use gray. The study suggests that standardization—and color—could meaningfully shift what ends up in shopping carts across the country.
Citas Notables
It is crucial that shoppers can recognise and understand the information at a glance. A multi-coloured label can be helpful here.— Dr. Clara Mehlhose, study leader
The greater visibility of the labels can make it easier to compare products and support people in making more health-conscious choices.— Isabelle Weiß, lead author
La Conversación del Hearth Otra perspectiva de la historia
Why does color matter so much more than the information itself? Isn't the rating the same whether it's green or gray?
The rating is identical, but the brain doesn't process color and grayscale the same way. Color triggers faster recognition and emotional response. In a supermarket, you have maybe two seconds per product. Grayscale requires you to read and interpret. Color lets you feel the answer.
So the red E label failed because people saw it but ignored it. What does that tell us?
It tells us that visibility alone isn't enough. A warning only works if the person is already motivated to listen. If someone wants that product—for taste, price, or habit—seeing red doesn't change their mind. The label can't override desire.
Does that mean the Nutri-Score is fundamentally limited?
Not limited, but honest about its limits. It's a tool for people who are already trying to make better choices. For them, color makes the decision easier. For people who aren't looking for guidance, no label will stop them.
What would actually work on the red E products?
That's the harder question. Maybe price. Maybe availability—if unhealthy products were harder to reach. Maybe social pressure. A label can inform, but it can't force. It can only make the path clearer for those already walking it.
So the real finding is about placement and consistency, not just color?
Exactly. Color on the shelf tag matters as much as color on the package. And if only some products are labeled, the system breaks down. You need the whole landscape to shift at once.