Label or taxes: Why not both? Testing nutritional mixed policies in the lab

We run an incentivized framed laboratory experiment to evaluate the interaction of labelling (Nutri-Score) and pricing policies (fat taxes and thin subsidies) on the food shopping of a sample of French consumers. Taxes and subsidies, designed to fit Nutri-Score, are differentiated according to their magnitude (large or small), and their salience (explicit or implicit). We exploit a difference-in-difference design, whereby subjects shop for real from a catalog of 290 products twice, first without any labelling nor pricing policy, and then a second time with one of five different combinations of labelling and pricing policies. Results show that: (i) when implemented alone, taxes and subsidies are less effective than labelling, especially when implicit and when small in magnitude; (ii) policies mixing pricing and labelling are strongly sub-additive; (iii) consumers would benefit from such policies in terms of expenditure at the expense of the State.