The Prisoner’s Dilemma in Everyday Life By Dr. Glenn Geher PH.D

The Prisoners Dilemma in Everyday Life | Fitness Hacks For Life

The Prisoners Dilemma in Everyday Life

How game theory can shed light on modern problems.


  • The game theory sees all actions as part of a game in which each individual is out to “win.”
  • Prisoner’s Dilemma is a particularly renowned example used by game theorists to understand social behavior.
  • When playing Prisoner’s Dilemma repeatedly, people are motivated to play nice. When playing Prisoner’s Dilemma once, they are not.
  • Some problems of the modern world can be understood in terms of the “one-off” Prisoner’s Dilemma.
The Prisoners Dilemma in Everyday Life | Fitness Hacks For Life
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Imagine this: You and an acquaintance, let’s call him Patrick, have the untoward idea of robbing a bank during broad daylight. To your chagrin, it doesn’t work out and you both end up downtown. The officers have moved you into separate quarters and you are each being grilled intensely by detectives who seem to be straight out of an SVU episode. And yes, you’re handcuffed and sitting in an austere room under a lightbulb.

The head detective comes in and does not mince words. If you want any chance of a light sentence, you’d better sing like a canary.

After an intensive grilling that is more stressful than anything you’ve ever experienced, it is clear to you that you have one of two choices. If you stay mum, you’re going up the river for a long time—perhaps five years or more. If you rat out old Patrick, you’ll definitely get a lighter sentence. And you may even be able to spin things in such a way that you get off with a stern talking-to and parole. To add to the intensity of the situation, you realize quite clearly that Patrick is in exactly the same boat.

So what do you do?

Prisoners Dilemma and Game Theoretical Approaches to Behavior

The scenario painted here refers to a classic game used by game theorists to understand the math that underlies behavior. It is called, appropriately, Prisoner’s Dilemma.1

In a game of Prisoner’s Dilemma, the question is whether people are likely to show loyalty to their partner (Patrick, in this case) or if they are likely to betray their partner to advance their own self-interests.

This game, which became extremely topical after being highlighted in Richard Dawkins’ game-changing book on evolution and behavior, The Selfish Gene2, can be used as something of a metaphor for understanding much of human social life. Nearly every day, we are faced with situations in which we have a choice to help someone else, at a cost to ourselves, or to not help and, thereby, advance our own self-interest.

In a prior post, I refer to this general dilemma as the fundamental human conflict, based largely on the work of renowned evolutionist David Sloan Wilson3, who talks about humans as regularly encountering a combination of pressures to help out others versus pressures to act selfishly.

We run into this broader kind of situation all the time, in fact. Here are but a few kinds of examples that you might run into in everyday life:

  • You are in a rush at the grocery store and the person in front of you accidentally drops a whole bag of fresh apples on the floor.
  • It is Thanksgiving morning and you have plans to visit your brother and his family. Your brother calls you at 8am and asks if you can come early to help him rake leaves.
  • You and your best friend are both huge Taylor Swift fans. A mutual acquaintance texts you saying that she has one extra ticket to Taylor’s concert at the Staples Center tomorrow night. She asks you to join. The show is sold out and there is no way that another ticket is going to materialize for your bestie.
  • You’re a college student and you and your buddy, both underage, were drinking beers in the dorm. The RA heard a rumor about your shenanigans and questions you about your role, suggesting that one way or another, someone is going to get into trouble.

And so on.

Every day is full of situations where we have choices to make. And quite often, the choice pertains to whether we should act in a way that helps another at a cost to ourselves, or just go ahead and do what’s in our own self-interest. In this way, life can be thought of a constant stream of Prisoner Dilemma kinds of situations.

Iterated versus One-Off Prisoner’s Dilemma

Mathematically oriented behavioral scientists have used the simple Prisoner’s Dilemma paradigm to explore all kinds of facets of human behavior. What would we expect people to do in this game? And what variables affect such behavioral decisions?

One critical factor that Dawkins2 talks about is this: Are you expecting to play this game with this same other people once? Or more than once?

In situations where the Prisoner’s Dilemma decision is essentially a one-off, people typically, not very surprisingly, tend to act in their own selfish interests. If you’re never going to see this person again, then there is little cost to simply going for broke at the other’s expense.

However, if you are expecting to interact with this same other person into the future, then you might want to think twice. As an example, if you’re playing Prisoner’s Dilemma with Patrick from the example above, and you plan to play against him tomorrow and the next day and the next, etc., you might think hard about whether to simply betray him to get yourself a relatively light sentence on this particular occasion. After all, Patrick is unlikely to forget such a betrayal very quickly. And he may well bite back next time around, leading to adverse long-term outcomes for you.

So when it comes to the Prisoner’s Dilemma kinds of situations, in short, people tend to behave differently if they are playing a one-off round or if they are playing one round of many (with this latter scenario referred to as iterative Prisoner’s Dilemma).

In one-off rounds of Prisoner’s Dilemma, people are more likely to betray the other and act in their own self-interests. In iterative rounds of Prisoner’s Dilemma, generally speaking, people are more likely to behave less selfishly. In short, an iterative Prisoner’s Dilemma context tends to breed niceness while a one-off context tends to breed nastiness.

Prisoner’s Dilemma, the Psychology of Strangers, and Evolutionary Mismatch

In life, sometimes, we interact with others whom we can fully expect to interact with again into the future. Such others might, for instance, include friends, relatives, and co-workers. In a sense, social interactions with such familiar others is akin to playing iterative Prisoner’s Dilemma. And as discussed above, we tend to be nicer to others when playing iterative Prisoner’s Dilemma compared with playing a round of one-off Prisoner’s Dilemma.

From an evolutionary perspective, we can think about this issue in terms of evolutionary mismatch, or the tendency for modern conditions to differ dramatically from the ancestral conditions that surrounded our evolutionary history.4

From the perspective of evolutionary mismatch, it is interesting to note that for the lion’s share of human evolutionary history, our ancestors lived in small nomadic tribes and were constantly surrounded by kin and other familiar others. In terms of Prisoner’s Dilemma, then, iterative Prisoner’s Dilemma was really the only game in town. And remember, iterative Prisoner’s Dilemma tends to foster cooperative, nice behavior.

But think about how things have changed, right!? These days, we interact with all kinds of people—many of whom are strangers. In fact, in any given day nowadays, we may interact with someone who uses a fake name and who lives across the world, such as sometimes happens when we call the customer service department of a large company. And think about this: When you are on hold with customer service and end up talking with someone whom you have never met and whom you likely will never see in your entire life, after waiting on hold for 90 minutes, are you always on your best behavior? I’m going to guess maybe not.

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Now step back and think about just how normalized it is to interact with strangers in the modern world. I bet if you counted the instances in a typical day, you’ll find that you may well interact with dozens of strangers on a daily basis. Each such interaction can be thought of as a case of one-off Prisoner’s Dilemma. And remember that simple rule derived from game theoretical analyses of behavior? People are more likely to behave in their own selfish interests when playing one-off Prisoner’s Dilemma compared with when playing iterative Prisoner’s Dilemma. Think about that.

The Bottom Line

In a sense, a large proportion of social interactions can be thought of in terms of Prisoner’s Dilemma, which pits our selfish interests against the motivation to cooperate with and help others. A simple rule of Prisoner’s Dilemma is this: When we play against someone else in an iterated manner, expecting to have further interactions with that same person, we tend to be nicer than when we are playing against someone in a one-off capacity.

Interacting with strangers, which is now commonplace in so much of the human experience, can be thought of as playing one-off Prisoner’s Dilemma. In modern conditions, we constantly find ourselves in situations, thus, that tend to inherently breed selfishness.

Want to understand why there is so much nastiness in the world today? Maybe the problem lies in the fact that so many human social interactions are between strangers who have no expectation of interacting with one another again. Perhaps this simple insight can help us create environments that are more conducive to helping, cooperation, and love.


1: Poundstone, William (1993). Prisoner’s Dilemma (1st Anchor Books ed.). New York: Anchor. ISBN 0-385-41580-X.

2: Dawkins, R. (1976). The Selfish Gene. Oxford: Oxford University Press.

3: Wilson, D. S. (2019). This View of Life: Completing the Darwinian Revolution. Pantheon: New York.

4: Geher, G. & Wedberg, N. (2020). Positive Evolutionary Psychology: Darwin’s Guide to Living a Richer Life. New York: Oxford University Press.

The Prisoners Dilemma in Everyday Life | Fitness Hacks For Life

Glenn Geher, Ph.D., is professor of psychology at the State University of New York at New Paltz. He is founding director of the campus’ Evolutionary Studies (EvoS) program.