Helping consumers with a front-of-pack label: Numbers or colors? : Experimental comparison between Guideline Daily Amount and Traffic Light in a diet-building exercise

• We compare experimentally Guideline Daily Amount and Traffic Light nutritional labels.
• Participants must compose a daily diet subject to nutritional constraints.
• GDA performs better than TL when subjects do not face time constraints.
• When time is limited TL and GDA have identical efficacy with 4 nutritional goals.
• When time is limited TL outperforms GDA with 7 nutritional goals.

This paper contributes to the debate on front-of-pack nutritional labels. Because of their dissimilar formats, Guideline Daily Amount (GDA) and Traffic Light (TL) may trigger different responses among consumers. While GDA is comprehensive and cognitively demanding, information is coarser and more salient in TL. We implement an incentivized laboratory experiment to assess the relative performance of GDA and TL labeling schemes in assisting consumers to build a healthy daily menu. Participants must compose a daily menu, choosing from a finite set of products, and are paid a fixed cash amount only if the menu satisfies pre-determined nutritional goals. Goals correspond to achieving the Guideline Daily Amount values of 1 (kcal), 4 (kcal, fat, sugar, salt) or 7 (kcal, fat, sugar, salt, fiber, vitamin C and calcium) different nutritional attributes. Three different labels, GDA, TL and a combined GDATL are provided. Results show that GDA performs better than TL when subjects do not face time constraints. When time is limited however, TL and GDA have identical efficacy with 4 nutritional goals, and TL even outperforms GDA with 7 nutritional goals.