Do you prefer dogs or cats? Vanilla or chocolate? Winter or summer? The answers to these questions, while simple, are fun to give, because our responses broadcast a bit of information about our personality, values, and desires. But there’s also a serious side to these questions: Businesses can use this intrinsic desire for self-expression to get consumers to give more money — whether tipping a little extra or donating more to a charitable cause.

That’s according to a new paper published in the Journal of Marketing, co-authored by Wharton associate marketing professor Jonah Berger; Jacqueline Rifkin, assistant marketing professor at the University of Missouri-Kansas City’s Henry W. Bloch School of Management; and Katherine Du, assistant marketing professor at the University of Wisconsin-Milwaukee’s Lubar School of Business.

Berger and his co-authors call this method of inspiring giving “the dueling preferences approach,” which frames the act of giving as a choice. Berger spoke with Knowledge@Wharton about the researchers’ study, “Penny for Your Preferences: Leveraging Self-Expression to Encourage Small Prosocial Gifts.”

Knowledge@Wharton: How does answering questions about personal preferences make people want to give more money?

Jonah Berger: There’s a fundamental question that many organizations or people have thought about, which is, how do we increase prosocial behavior? If I’m the American Red Cross, how do I get more donations? If I’m a barista at a coffee shop or a waiter at a restaurant, how do I get people to tip me? It’s obviously very hard. Lots of people mean to donate — they want to donate — but there are lots of causes and things going on.

We all love self-expression. We do it all the time through our cars and clothes and music. My co-authors and I wondered whether we could leverage this tendency and this desire for self-expression to encourage prosocial behavior. Part of this idea actually started from something we saw in coffee shops. You might walk into a coffee shop, and rather than having a tip jar there for you to drop in a buck or two, there are two jars with pictures on them. One might say “dog,” and one says “cat.” They might say “vanilla ice cream” or “chocolate ice cream.” Or they might say “Star Wars” or “Star Trek.”

American Red Cross donations increased 28 percent when tied to a vote on ice-cream flavor preference, says professor Jonah Berger.

Coffee shops are using that approach for a reason. They think it’s engaging their customers in some way and hopefully increasing tips. But we wondered: Does it work? Does it work all the time? Can we apply this more broadly? Knowing that people drop in a couple of extra cents for cats vs. dogs is nice for a coffee shop. But if I’m the leader of a big nonprofit, could something like this be useful for me? Can it tell us something broader about human behavior and ways that organizations can leverage these insights to increase prosocial behavior?

K@W: How did you study this? It seems subjective, so how did you make this analytical and objective?

Berger: One experiment we did was very much in the exact setting we talked about: a local coffee shop. We went in, and for different periods of time, we had different tipping situations. Sometimes, there would be a single jar that would say “Tips.” Other times, we randomly manipulated whether it had just a jar or this idea of dueling preferences — these two things that customers could vote on. They could choose cats or dogs through their tipping. We manipulated the time of day across multiple days, counterbalancing for everything — almost like an A/B test — to get a sense of what affects donations. You could say, “Well, hold on. You’re asking people to make a choice. Cats and dogs have nothing to do with tipping. Maybe it’s going to decrease donations. Maybe people are going to feel overwhelmed. They’re not going to make a choice.” But that’s not what happened. Giving people a choice mattered. Just making two jars and putting “cat” and “dog” on them led people to tip more than twice as much compared to a tip jar.

It wasn’t just restricted to tipping. We did a very similar experiment with donations to the American Red Cross. Rather than simply asking for donations — and that’s what we did for some people — some people were asked to donate by voting. Would you prefer chocolate ice cream or vanilla ice cream? Again, chocolate and vanilla ice cream have nothing to do with the American Red Cross. You could say, “Well, hold on. Won’t people think this is frivolous or doesn’t matter? It’s not going to help.” But that’s not what occurred. In fact, just the opposite: It increased donations by 28 percent.

K@W: Were you surprised by the experiment results, or did they line up with what we already know in the literature about identity and consumer behavior?

Berger: I was surprised by the size of these results. This isn’t a couple of pennies here and there. A 28 percent increase to the American Red Cross is a big deal. That’s a lot of money for that organization. I was certainly surprised by the size of the effect, but it was also interesting to see when this happens and why. I’m not suggesting to just give anybody a choice, or that any choice will work. It really has to be a way for people to express their preference. It has to be something that they care about, and they feel that expressing their preference on that dimension is diagnostic of who they are.

K@W: Given this information, what can marketers, managers, or even charity directors do to help increase giving?

Berger: I think the place to start is to stop just thinking about you. Your cause is very important, but think about your audience. What this research shows is, yes, if I’m the American Red Cross — or whichever organization — I can go out there and say, “This is an important problem. Please donate money to this problem.” And I will get people to donate. I will get a set of people who have donated in the past to donate. Those aren’t small circles of people. But if I want to move beyond those circles, I have to think bigger. I have to think beyond just my cause and people who believe in that cause to begin with and start thinking about, “Well, what do those folks care about?”

Even people who may care about the cause to begin with — what’s a way to motivate them to give? This isn’t just about making it a game, though it does feel a little bit like a game. It’s really about allowing them to express themselves. Maybe your local grocery store does this competition where they say, “Collect receipts, give them to your local school, and the school that gets the most receipts gets a big donation from the grocery store.” That’s not just allowing people to express themselves, but to compete.

If I were a marketer, a manager, a charity director, I would think about how to harness self-expression. I would think about the right opportunity to give people the right choice. How can I motivate my audience to give by providing them an opportunity to express their preferences?


Published as “On Pets, Ice Cream, and Charity” in the Fall/Winter 2021 issue of  Wharton Magazine.