Imagine being in the following situation. I tell you that I gave someone $6 and told them they could give as much or as little of it to you as they wanted (and keep the rest for themselves). I hand you an envelope that contains the amount they gave you. You eagerly open the envelope, shaking it to reveal your bounty, only to find that this previous person left you nothing. Zero point zero zero dollars. Take a moment to think how you’d feel – and what words come to mind to describe the guy who stiffed you.

Now imagine I then gave you another $6, and asked you give as much as you wanted to a new person and keep the rest. It’s like being cut in line: having been cut, would you turn the other cheek or make sure to cut somebody else? Would you pay the greed forward?

Before I tell you how much people paid forward in this situation, consider two more possibilities. What if you’d opened the envelope and the previous person had been amazingly generous, giving you all $6? Or what if they’d treated you fairly, giving you $3 and keeping $3 for themselves? Again, given a new $6 to split it with a new person, would you pay forward that generosity? Would you pay forward that fairness?