The Surprising Sale

A while ago, I encountered such a finding when I read a study that gave volunteers an energy drink designed to increase mental abilities. Some volunteers were charged the retail price of the drink ($1.89); others were told, because the researcher had made a bulk purchase, they’d have to pay only $0.89.

Both groups were then asked to solve as many mental puzzles as they could in thirty minutes. I expected the second group, feeling good about the price break, would have tried harder and solved more problems. Wrong, the…