Cooperation between people isn't necessarily increased when they are threatened with punishment. Fox Photos/Getty Images

An international team of researchers examined the sociological theory that punishment could be used to coerce individuals into increased cooperation with each other, and found it not quite right. Instead, they found the threat of punishment did not increase cooperation among people at all, perhaps because punishment was viewed differently by the punisher and those being punished.

Cooperation with others can sometimes come at a cost to some of the cooperating individuals. Someone sharing food during a time of scarcity reduces personal, precious ration, and someone warning others of an impending disaster loses time that could be spent on self-preservation. For individuals of species that is considered inherently selfish, such behavior is perplexing and theorists have said punishment maybe one of the reasons why we cooperate despite the selfish streak.

Led by Marko Jusup of Hokkaido University in Japan and Zhen Wang of Northwestern Polytechnical University in China, the researchers conducted a “social dilemma experiment” on 225 students in China, using a variation of the “prisoner’s dilemma” game often used in studies of this sort. The students were divided into three groups, and they played 50 rounds each of the game, which was testing if including the option of punishment would improve cooperation.

In simple terms, the prisoner’s dilemma works by asking two individuals, both designated prisoners for the purposes of the game, whether they choose to either remain silent (cooperate) or spill the beans (defect). If both choose to cooperate with each other, both are rewarded with a lesser sentence. If one chooses to cooperate and the other to defect, the former is punished for longer than the first scenario, while the latter is freed. If both defect, they both serve an equal sentence whose duration is somewhere between the first and second scenarios.

In the social dilemma experiment, the first group of students played the game with points (that were later converted to monetary compensation) instead of prison sentences. But instead of two participants, each round had three, with one student facing two opponents at a time.

In the first group, the two opponents changed with every new round. In the second group, the students faced the same opponents through all 50 rounds. The players remained the same across rounds even in the third group, but a new element of punishment was introduced. Choosing that option would reduce by a small amount the punisher’s points, and by a larger amount, points of those being punished.

Since the threat of punishment was a clear indication to the opponents that it was in their best interest to cooperate with the player, it was expected that the existence of that option would lead to higher cooperation in that group.

The first group fared the worst, with only a 4 percent cooperation rate seen among the constantly changing players. The second group, where the players remained the same, performed the best with 38 percent cooperation level. The third group, with the implied punishment option, actually fared slightly worse, with a 37 percent level of cooperation. In this group, some players were seen replacing defection with punishment.

“While the implied message when punishing someone is ‘I want you to be cooperative,’ the immediate effect is more consistent with the message ‘I want to hurt you,’” the researchers wrote in the study that first appeared online Dec. 19 in the journal Proceedings of the National Academy of Sciences, under the title “Punishment diminishes the benefits of network reciprocity in social dilemma experiments.”

Talking about the prevalence of punishment in human societies, Jusup said in a statement Wednesday: “It could be that human brains are hardwired to derive pleasure from punishing competitors.”

“However, it is more likely that, in real life, a dominant side has the ability to punish without provoking retaliation,” Wang added.