The script is so deeply ingrained that you don't even need to think about it. When you do a favor, and someone says "thank you," the automatic response is "you're welcome." It's a basic rule of politeness, and it signals that you accept the expression of gratitude -- or that you were happy to help.

But according to one leading psychologist, this isn't the best choice of words. After four decades of studying persuasion, Influence author Robert Cialdini has come to see "you're welcome" as a missed opportunity. "There is a moment of power that we are all afforded as soon as someone has said 'thank you,'" Cialdini explains. To capitalize on this power, he recommends an unconventional reply:

"I know you'd do the same for me."

There are at least three potential advantages of this response. First, it conveys that we have the type of relationship where we can ask each other for favors and help each other without keeping score. Second, it communicates confidence that you're the kind of person who's willing to help others. Third, it activates the norm of reciprocity, making sure that you feel obligated to pay the favor back in the future.

As Guy Kawasaki writes in Enchantment, "Cialdini's phrase tells the person who received your favor that someday you may need help, too, and it also signals to the person that you believe she is honorable and someone who will reciprocate. If this is the spirit in which you're saying it, your response is far more enchanting than the perfunctory 'You're welcome.'"

Although the logic is compelling, and I'm a longtime admirer of Cialdini's work, I've never felt comfortable saying this phrase out loud. At first I thought I was too attached to politeness rules. How could I leave a "thank you" just hanging in the air without the proper acknowledgment? Awkward.

That explanation fell apart, though, when I realized I could just combine politeness with Cialidni's response: "You're welcome -- I was happy to do it. I know you'd do the same for me."

It didn't change my mind. The response still left a bad taste in my mouth. Eventually, I realized the problem was the subtle appeal to reciprocity. There's nothing wrong with trading favors or asking others to repay the help you've given, but when I chose to help people, I wanted to do it without strings attached. I didn't want to leave them feeling like they owed me. So I stuck with the familiar, banal "you're welcome," which was mildly dissatisfying. Why do we utter this strange phrase?

In English, it's a relatively new arrival. Over the past century, "you're welcome" has evolved to connote that it's my pleasure to help you or "you are welcome to my help," which we tend to say more directly in other languages like Spanish and French ("the pleasure is mine," "it was nothing," "no problem"). Is there a better alternative?

I stumbled upon an answer after meeting Adam Rifkin, a serial entrepreneur who was named Fortune's best networker. He goes out of his way to help a staggering number of people, doing countless five-minute favors -- making introductions, giving feedback, and recommending and recognizing others. After Rifkin does you a favor, it's common for him to reach out and ask for your help in return.

At first, it seems like he's just following the norm of reciprocity: since he helped you, you owe him. But there's a twist: he doesn't ask you to help him. Instead, he asks you to help him help someone else.

Rifkin is more concerned about people paying it forward than paying it back. In his view, every favor that he does is an opportunity to encourage other people to act more generously. That way, a broader range of people can benefit from his contributions.

After watching Rifkin in action, it dawned on me that Cialdini's line could be adapted. Instead of "I know you'd do the same for me," how about this response?

"I know you'll do the same for someone else."

Just like Cialdini's reply, it affirms your character as a person who's happy to be helpful. Unlike his version, it doesn't deliver the implicit message that you're indebted to me, and I'm waiting for you to repay it.

It's just a sentence, but the underlying values have the potential to fundamentally change the way that people interact. In traditional direct reciprocity, people trade favors back and forth in pairs. In contrast, Rifkin's approach is called generalized reciprocity. As described by political scientist Robert Putnam in Bowling Alone, "I'll do this for you without expecting anything specific back from you, in the confident expectation that someone else will do something for me down the road."

If you follow this approach, when you really need help, you have access to a broader range of potential givers. If you stick to direct reciprocity, you can only ask people you've helped in the past or might be able to help in the future. In generalized reciprocity, you can extend your request to a wider network: since you've given without strings attached, other people are more inclined to do the same. In fact, social scientists James Fowler and Nicholas Christakis have conducted experiments showing that acts of giving often spread "up to three degrees of separation (from person to person to person)."

So next time someone expresses appreciation for your help, it might be worth stretching beyond politeness to ask them to pay it forward. I know you'll do that for someone else.

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Adam is the author of Give and Take, a New York Times and Wall Street Journal bestseller on how helping others drives our success.

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