Americans’ difficulty saving, Daniel Eckert told me recently, is a textbook example of how brains wired to reckon with short-term threats and opportunities struggle to think about long-term consequences—and struggle even harder to take current action to stave off future disaster. Eckert, who oversees Walmart’s financial-services businesses, became interested in behavioral economics while earning his M.B.A. at the University of Chicago in the early 2000s.

Take a walk through a retail store—a Walmart, let’s say. You’ll pass heaps of products in every category, big signs advertising prices that seem too good to pass up, TV screens touting bargains galore. I shop at Walmart frequently, and somewhere in the long walk from the dog-biscuit aisle to the yogurt case I am at the very least tempted to buy something I didn’t know I needed when I arrived.