New research reveals that people are irrationally but effectively motivated by the idea of completing a set, even if it means working harder or spending more money—with no additional reward other than the satisfaction of completion and the relief of avoiding an incomplete set. Imagine arriving at your boss’s summer BBQ and presenting her with five beers in a box designed to hold six. No matter that your favorite craft beer store permits you buy bottles one at a time. Chances are you’d still buy six, just to fill all six spaces in the box.
“People really don’t like to leave things incomplete,” says Kate Barasz, an assistant professor of marketing at IESE Business School and lead author of the paper “Pseudo-Set Framing,” written while she was a doctoral student at Harvard Business School. The term “pseudo-set” refers to the idea that the set is kind of arbitrary—manufactured for the sole purpose of creating the idea of wholeness.



