Inattention or Avoidance? A Field Infrastructure for Testing Nutritional Labels Online

We build a field infrastructure to test how nutritional information should be displayed online. Its core is a browser extension that changes what Walmart.com shows next to each product and records what shoppers look at and buy, in their own accounts and with their own money. We use it to ask whether shoppers who leave nutritional information unread do so because reading it costs effort or because they would rather not know. In a pilot with 110 U.S. households, the extension shows participants nothing, a 0-100 nutritional score, the score with the nutrients and additives behind it, or the same label behind one click. We find that participants leave closed 96 percent of the labels one click away, and that they open least often the labels of products that score poorly and that they already buy. Participants who see the score alone fill their carts like those who see nothing. Participants who also see the nutrients and additives choose products that score 4.5 points higher within the same type, about 7 percent of the average score, and are 9 percentage points less likely to buy a product rated poor, while participants who have the same label behind one click do not. Participants attribute the same value to keeping the extension in every condition. We read these patterns as preliminary, since they come from a small pilot. Researchers and platforms could use this infrastructure to test health policy interventions, such as the design of nutritional labels, efficiently, in real purchases and before adopting them.