The prisoner’s dilemma is one of the most famous paradigms and at the same time one of the most discussed case studies in both economics and psychology introductory classes. Basically, two prisoners are each isolated from one another and are presented with two choices: either they turn the other in (sabotage) or remain silent (cooperate). Now, from here on it varies, but let’s say if one of the paired prisoners testifies, and their partner remains silent, the partner gets three years and the “rat” goes free. If both testify, both get two years. If both stay silent, both get only one year.

Now, game theory states that in such a confrontation betrayal is the dominant strategy since it offers the a slightly higher payoff in a simultaneous game. Economists refer to this as the “Nash equilibrium” after the Nobel Prize recipient John Nash and feature film subject in the Oscar winning biopic “A Beautiful Mind”.

Truth is, this game has been played loads of times before, and apparently game theory’s right: betrayal is the dominant outcome. But not necessarily and not always. For instance, one of the most interesting renditions of the paradigms was made using two study groups: one made out of students and the other out of actual inmates. The study was performed by  two University of Hamburg economists who wanted to analyze the behavioral differences between the two. The outcome was unexpected, to say the least.

Trust or not: the prisoner’s dilemma

A group of prisoners in Lower Saxony’s primary women’s prison was selected to play the same game as another separate group made out of students, through both simultaneous and sequential versions of the game. Naturally, no prison terms cuts could be made so as rewards money was offered to students, while the equivalent in coffee and cigarettes were offered to the inmates.

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The researchers found for the simultaneous game, only 37% of students cooperated, while inmates cooperated 56% of the time.

On a pair basis, only 13% of student pairs managed to get the best mutual outcome and cooperate, whereas 30% of prisoners do.

In the sequential game, far more students (63%) cooperated, so the mutual cooperation rate skyrockets to 39%, whereas for prisoners, it remains about the same.  It’s worth noting, though, that the simultaneous game requires far more blind trust from both parties, and the prisoners were far more keen on showing trust first than the students.

Now, everybody assumed that prisoners, seeing how they’re living in a jagged and stressful environment, will defect in larger proportions than the students. The opposite occurred however and while the payoffs weren’t that great (an actual prison sentence reduction would have most likely rendered different results) the paper, published in the Journal of Economic Behavior and Organization, demonstrates that inmates aren’t that calculated and untrusting as society is quick to label them the moment they set foot in a correctional facility.