This is part II of  an ongoing series about promoting cooperation in society. You may want to check out part I first.

Interactions that are both repeated and personal inspire a degree of cooperation that does not occur when communities and individuals are isolated.

In the first part of this series, I discuss how interaction can improve cooperation among people of different groups. I would like to dive a bit deeper into the logic of why average cooperation would increase due to greater interaction.

Recall that I only expect cooperation to improve if interactions are repeated and personal. Let’s take a look at each of these conditions seperately.

Repeated Encounters

Repeated encounters encourage cooperation because your reputation is on the line. If you consistently behave like a jerk, lie, or are unpleasant to be around, the people who you interact with will exclude you from opportunities. In a work setting, you may lose your job or promotion opportunities. In the market, you may lose customers. Most people understand that their behavior determines their personal outcomes in the future, so they choose to be cooperative.

[Note: People need only to expect repeated encounters for them to consider their reputations in decisions]

Now let’s consider what happens when a person does not expect to ever encounter a person again. Reputation does not factor into the individual’s decision-making process, so they are more likely to behave in a manner that is embarassing, rude, or foolish. They are not concerned about losing opportunities.

We can also think of repetition as regulating behavior through costs of reputation. When repetition does not occur, the reputation costs associated with not cooperating are low. Low reputation costs lead people to be more likely to behave in a manner that is disapproved by others. However, when people expect repeated encounters, the costs of reputation can be very high. This cost may discourage behavior that is uncooperative or socially disagreeable.

Personal Interaction

Personal interaction may improve cooperation between both friends and strangers. As personal interaction increases, we expect cooperation to increase. This is a well-observed phenomenon in psyschology known as the mere-exposure effect, a.k.a. the familiarity principle. But why is this so?

[Please note that, while personal interaction clearly increases cooperation, the mechanism is not clear.]

A Philosophy of Empathy

There are several ways to think about this trend. One angle is philosophy. In Theory of Moral Sentiments, the moral philosopher Adam Smith argued that good behavior is regulated by empathy. By being in the presence of another person, we are able to see their expressions and relate to their moods and thoughts. From Smith’s view, a moral person with a strong sense of empathy will feel pain or sadness when others around him feel pain or sadness. Likewise, the moral person feels happiness when others feel happiness. This theory suggests that empathetic people are inclined to behave in a way that makes others happy (cooperation) while avoiding behaviors that invoke negative emotions.

This philosophy of empathy has merits when explaining why personal interaction increases cooperation, but it assumes that people who exhibit good behavior are highly empathetic. The philosophy offers little explanation of why people are empathetic, but personal interaction should be considered. By speaking to a person face-to-face, we can relate to their situation (through language, expressions, physical presence). Perhaps this greater familiarity allows empathy to regulate behavior in the way Adam Smith suggests. Unfortunately, empathy is difficult to measure. This argument may be a hard sell without data.

The Evolutionary Perspective

I mentioned in the first post of this series that people are biologically wired to place their trust in people who look like them. Humans can rely on reason and experience instead of instinct, so this evolutionary perspective is simply a tendency. By increasing personal interaction, we begin to understand people beyond appearances and first impressions. Personal interaction allows us to form organizations and communities beyond basic family units because we find familiarity through common goals and interests. With institutions and technology that promote personal interaction, people can discover these common traits to improve cooperation.

The takeaway here is that biology may be the cause of why familiarity increases cooperation, but the traits leading to familiarity depend on reason and experience.

An Economic View: Incentives of Personal Interaction

Adam Smith’s theory depends on empathy, but we can also make the case for a more selfish reason for cooperation during personal interactions. Let’s take a look at the incentives associated with being friendly and cooperative in an interaction. For many people, good interactions (friendly, helpful, or otherwise positive) trigger the reward center in the brain. I will call this the feeling of charity. This feeling of charity makes people feel good, so they are more likely to repeat the behavior in the future. Overtime, the feeling of charity causes people develop positive associations with the people they engage with. These positive associations increase cooperation among individuals and groups.

Now consider what happens when we choose bad interactions (conflict). Instead of enjoying the feeling of charity, we experience frustration, anger, and other stress responses. I think it is fair to suggest that, if given the choice, people would choose the feeling of charity from cooperation over the conflict from disagreeable behaviors.

The desire for acceptance may also encourage cooperative behavior in personal interactions. In this case, the fear of rejection should cause people to avoid violence, rudeness, and other behaviors that are socially disagreeable. This desire to belong may relate to the evolutionary perspective that I mentioned earlier.


The mechanisms of how repeated personal interactions influence cooperation are not always clear. They result from a blend of psychological and economic factors. However, we do not need to know all of the mechanics to realize that people benefit from cooperation when repeated face-to-face interactions are expected. At the individual level, cooperation is the rational choice.