Why Do We Choose To Team Up With Some People Over Others?

Researcher Nathan Dhaliwal helps us understand why having a cooperative attitude is so important to our social relationships.

By Mark Travers, Ph.D. | May 6, 2023

A new study published in the Journal of Experimental Psychology: General offers a scientific explanation for why we sometimes prefer to team up with people who have fewer resources or less ability.

I recently spoke with Nathan A. Dhaliwal, a researcher and Ph.D. student at the University of British Columbia, to gain insight into this line of reasoning. Below is a summary of our conversation.

What inspired you to investigate the topic of partner choices? How did you study it, and what did you find?

Partner choice is the behavior of choosing certain people as partners over others. Interestingly, this behavior has been identified by evolutionary scholars as likely playing a key role in incentivizing cooperation within our species.

For example, imagine a team of people who cooperate to achieve a common goal. Such teams are inherently susceptible to a member of the team deciding to slack off and not contribute. One way to dissuade such behavior is for there to be uncertainty about whether one will be chosen as a cooperation partner in the future. This can incentivize people to continue cooperating, even to the point of competing to be the most cooperative in the group.

Now, what is peculiar is that people prefer cooperativeness in their partners to such an extent that they often forgo potential partners that have more resources in favor of someone with a history of being cooperative. This is a costly decision and therefore presents an evolutionary puzzle: Why would people choose the person who brings fewer resources to the table?

We explored the hypothesis that this costly decision can make adaptive sense if by choosing the less resourceful but more cooperative partner, the chooser themselves gains reputational benefits.

We tested this hypothesis and found support for it across nine experiments. We had participants read vignettes which described a person deciding between certain types of partners for various activities, and we found that when a chooser favored cooperativeness in others, the chooser appeared more moral in the eyes of the participants.

In layman terms, could you help understand 'cost signaling theory'?

Costly signaling theory has its origins in evolutionary biology. It posits that for a trait or behavior to serve as a signal, some types of actors must find the trait or behavior too costly to exhibit.

Perhaps the most well-known example of this is the peacock's tail. On its face it would seem to be a very strange trait to evolve; the cumbersome and conspicuous tail would certainly make the peacock prime picking for a predator. In fact, Charles Darwin was so baffled by the peacock's tail that he remarked, "the sight of a feather in a peacock's tail, whenever I gaze at it, makes me sick."

Fortunately, costly signaling theory helps solve this puzzle. It explains that only a peacock of superior genetic quality could afford to expend the biological resources necessary to grow such an elaborate tail. Those peacocks of lesser genetic quality must reserve their biological resources for more mundane tasks. As a result, an elaborate tail signals to peahens that the peacock is of high genetic quality and hence a worthwhile mate.

We applied this theory to understand human partner choice decisions. Similar to the peacock growing its costly tail, people often make costly partner choice decisions to favor cooperativeness over resources.

We put forth the idea that only choosers who are sufficiently cooperative can make it worthwhile to choose a less resourceful but more cooperative partner, because only a cooperative person can keep relationships going for long enough to derive sufficient benefits from them. Choosers who are less cooperative require immediate benefits, because their low cooperativeness will cause others to defect in response.

Therefore, only people who meet a certain threshold of cooperativeness should make this costly partner choice, allowing for such partner choice decisions to serve as a signal, distinguishing those who can maintain a long-term cooperative relationship from those who cannot.

According to your research, how does one define an 'able partner' and a 'willing partner'?

We follow previous research in using the terms 'able' and 'willing' to refer to two dimensions that a person can vary on.

In this literature, ability refers to the capability to benefit another person, whether it's via one's wealth, health, intellect, or another form of social capital. Willingness refers to the inclination to benefit another person. This can be shown by having a history of being cooperative, such as being generous or trustworthy or respectful or fair.

Ability and willingness are what underlies the dimensions of competence and warmth, which are commonly studied in the field of social psychology.

Are there any words of wisdom you have to help someone make healthy partner choices? In lieu of your research, what factors should be considered while doing so?

This research was entirely descriptive in its focus, so I wouldn't want to draw too many normative conclusions from it. There are two ideas, however, that may be worth considering.

1. When one is overcome with the temptation to chase affiliations with those who are rich and famous, one might be wise to consider the long-term consequences. Instead, it can really pay to build social connections with those who have shown a keen interest in being trustworthy and loyal.
2. One should also keep in mind that the allure of appearing virtuous could lead one to choose nice and friendly people for jobs, despite them being ill-suited for the role.

We must remember: despite the possibility of appearing virtuous for choosing a willing partner, when it comes to choosing people for jobs or other opportunities, it is likely best to be meritocratic and base such decisions on a person's level of competence.

Do you have plans for follow-up research? Where would you like to see this research going in the future?

At the moment I do not have plans for follow-up research on this specific topic, but I do want to highlight an important paper that was published at about the same time that our paper was published: Why warmth matters more than competence: A new evolutionary approach by Adar Eisenbruch and Max Krasnow.

This paper by Eisenbruch and Krasnow also tries to solve the evolutionary puzzle of why people value willingness/warmth over ability/competence in others. They posit that throughout human evolutionary history there was far greater variability in willingness/warmth traits than there was in ability/competence traits.

For example, within a single tribe there would be people who would be exceptionally caring and helpful toward you and there would also be people inclined to be extremely violent toward you. In contrast, there was likely far less variance in people's skills and abilities.

For example, there were hunters of great prowess and those of lesser skill, but such variance didn't match the variability in willingness/warmth traits that existed in such populations. And due to this asymmetry in the distribution of traits, Eisenbruch and Krasnow argue that natural selection would have favored the focusing on another person's willingness/warmth traits over their ability/competence traits.

An interesting area to explore in future research could be to understand how the signaling consequences of partner choice decisions relate to Eisenbruch and Krasnow's research on the distribution of willingness/warmth traits versus ability/competence traits.

More broadly, I think Eisenbruch and Krasnow's paper and our own research both demonstrate the insights that can flow from first identifying a costly behavior that humans engage in and then trying to understand its uses in the principles of natural selection. I look forward to seeing future research use such principles to shed light on other enigmatic human behaviors.