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Prisoner's Dilemma

The prisoner’s dilemma is not a novel concept. Traditionally, the description for this hypothetical scenario goes as follows:

Two criminals are arrested, but police can’t convict either on the primary charges, so they plan to sentence them both to a year in jail on a lesser charge. Each of the prisoners, who can’t communicate with each other, are given the option of testifying against their partner. If they testify, and their partner remains silent, the partner gets three years and they go free. If they both testify, both get two. If they both stay silent, they both get one.1.

In this situation, it is the most advantageous for the prisoner’s to betray each other because that presents the greatest payoff in the end. However, that outcome can only be achieved if one of the prisoner's remains silent, while the other does not. The chart below presents the possible actions: 

The idea here is that individuals are thought to be most likely to take part in the action which is in their own self-interest. Furthermore, it is assumed that these two prisoners are members of the same gang, but there is no chance for retribution after the game. Therefore, since there is no real disadvantage to being unloyal to the other prisoner, it is thought that these prisoners will be untrusting and not cooperative.

Surprisingly, a study done on prisoners from two prisons in 2013 found that prisoners were more cooperative in comparison to students, when this game was played1. In simultaneous games, student’s cooperation increased, whereas the cooperation of prisoners remained the same1. When simultaneous games are played, an individual has the opportunity to betray another individual for previous decisions. However, in a rational sense, the most logical decision is to continually betray the other player.

The prisoner’s dilemma is a theoretical concept which is related to understanding the behaviour of individuals. It is related to emotions such as cooperation and morality, which both developed and evolved through biological evolution.




1. Business Insider. (July 21, 2013). They finally tested the 'Prisoner's Dilemma' on actual prisoners - And the results were not what you would expect. Retrieved from

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Tutorial: Game Theory Questions

1. [5 Marks] (Selfish and altruistic social behavior) Two people enter a bus. Two adjacent cramped seats are free. Each person must decide whether to sit or stand. Sitting alone is more comfortable than sitting next to the other person, which is more comfortable than standing. (a) Suppose that each person cares only about he