Human societies maintain their cohesion through a mix of cooperation, competition and punishment. The latter is commonly held to be a human technology designed to elicit cooperation from unwilling parties.
The broader question that researchers have been studying for many decades is why does natural selection favour cooperative behaviour among individuals who are inherently selfish?
On the face of it, collective behaviour is highly beneficial – sole individuals are much less likely to survive than individuals in groups. On the other hand, cooperation is usually quite risky, and sometimes no more beneficial than free-riding.
To find out if punishment is useful in maximising cooperation, an international group of researchers enrolled 225 students from China to play a version of the “prisoner’s dilemma” – a classic thought experiment developed by researchers working on game theory.
Students were divided into three groups, with each student playing the game for a total of 50 rounds.
In one group, students played against two different participants every round, choosing either to “cooperate” or to “defect”. Points were assigned based on the choices made by all players, whereby a collective decision to “defect” awarded 0 points, collective decision to “cooperate” – 4 points, and unilateral decision to defect (with other players choosing to cooperate) – 8 points.
In the second group, students played all 50 rounds against the same two participants, allowing them to learn each other’s characteristics.
The last group was the same as the second, except for the introduction of the option to “punish”, which resulted in a small reduction in points for the punisher, and a larger reduction for the punishees.
Results showed that cooperation in the first group was only 4%, as compared to 38% in the second. The most interesting finding, however, was that introducing punishment did not increase cooperation – the last group came in at 37%.
The reason for this, researchers speculate, is that instead of encouraging people to cooperate, punishment is often perceived as a desire to hurt, reducing people’s interest in cooperation and leading them to behave less rationally.
It could also be that humans are hard-wired to enjoy seeing offending parties harmed, and groups wielding power can get away with it without facing retribution.
The study was published in the Proceedings of the National Academy of Sciences.