People’s desire to reciprocate acts of kindness is surprisingly robust

Prosocial behaviour can sometimes feel pretty paradoxical: you're doing something to benefit somebody else, but it can come at a cost to yourself. That cost could be small — getting up to make a cup of tea, for example — or could be more significant in terms of time, money, or energy.

Research has already established that there are four main forms of "reciprocity" that drive people to behave prosocially: wanting to do something nice for somebody who had been kind to you (direct reciprocity); doing good in the presence of people who might reward your generosity (reputational giving); paying it forward after experiencing kindness yourself (generalised reciprocity); or doing something for someone you'd seen be generous (rewarding reputation).

But most of these motivations have been studied individually: what happens when — as in real life — they all occur at once? In a new study published in Science Advances, David Melamed and colleagues find that people intrinsically want to help each other — even when those drivers seem like they are competing with one another.

To understand how these four motivations work together and overlap in a real life setting, the researchers asked participants to make a series of decisions about gifting tokens to other participants, who they did not realise weren't real. For each decision, participants had a pool of 10 tokens: any they didn't allocate to other users, they were told, they would keep for themselves. At the end of the study, these tokens would have a monetary value, so it was actually costly to gift to others but beneficial to receive tokens from others (received tokens were worth twice as much).

To mimic the four drivers of reciprocity, participants saw information about what others had done with their tokens in each series of decisions. To imitate direct reciprocity, for instance, participants were told another participant had given them a number of tokens, while to imitate reputational giving they were told one participant would know how many tokens they had given to another.

Importantly, a series of decisions contained between one and four of these different scenarios, allowing the researchers to look at how the factors interacted with one another as they would in the real world.

Individually, motivators for prosocial behaviour were as expected: participants were more likely to give more if they knew they would be directly rewarded themselves (direct reciprocity), if they were given information about one or two others who had given to them (generalised reciprocity), if there had been others to witness their giving (reputational giving), and if they had seen another participant being generous (rewarding reputation).

More interestingly, however, these factors barely ever seemed to "crowd" each other out. For instance, it didn't matter if participants saw someone giving tokens to others and were given information about those who had given to them directly — they still shared their tokens with both of those individuals. These findings indicate that people are likely to be driven to act in a prosocial way no matter how different motivators are combined.

This is particularly interesting when considered through the lens of self-bias: you might expect that someone would be less likely to reciprocate a favour done for someone else if they are also focused on repaying a favour that had been done specifically for them. But this wasn't the case.

So when you're fed up with the world, it might be worth bearing these results in mind. Because even when it costs someone something, they're still likely to help you out — and that potential for prosocial behaviour is most certainly a cause for cheer.

"From an evolutionary perspective, it's kind of perplexing that it even exists, because you're decreasing your own fitness on behalf of others," Melamed concludes. "And yet, we see it in bees and ants, and humans and throughout all of nature."

Further reading

– The robustness of reciprocity: Experimental evidence that each form of reciprocity is robust to the presence of other forms of reciprocity

About the author

Emily Reynolds is a staff writer at BPS Research Digest