Ever played the dictator game? It’s a test that psychologists use to measure people’s altruism. That is, how much you’re willing to share.

One person is given ten dollars and the power to give their partner as much (or as little) as they want. But researchers James Andreoni and Justin M. Rao found that making one change to the rules makes a huge difference in how selfish people are. What is that one thing? Talking.

Turns out that when the person receiving the money remains silent, the giver is likely to keep all the cash. But when the receiver is allowed to talk, the allocator is more willing to be generous. Not only that, but according to the study “when empathy was heightened by putting allocators ‘in the receivers shoes,’ altruism appeared as if recipients had been able to ask, even when they were silent.”

The moral of this story? Communication is as good as gold.