A psychology study offers insight into why psychopathy — a largely “inhuman” personality trait — continues to exist across time and cultures. During a prisoner’s dilemma game, subclinical psychopathy was associated with a strategic social strategy that suggests fitness advantages to the trait. The findings were published in the Proceedings of the Royal Society B: Biological Sciences.
Clinical psychopathy is defined by anti-social, amoral behavior, a lack of empathy for others, and egocentricity. This collection of behaviors is in stark contrast to the sociability that makes us human, such as the ability to cooperate and maintain reciprocal relationships with various people. A study led by Matthew M. Gervais asks the question of why this trait continues to show up in society and proposes that a better understanding of subclinical psychopathy might provide the answer.
There is some evidence that subclinical psychopathy involves the strategic exploitation of others. This effect specifically involves primary psychopathy, which is defined by callousness and interpersonal manipulation. While people with clinical primary psychopathy tend to defect in all situations, people with subclinical levels defect strategically, opting to cooperate in situations when it will maximize their gains.
To explore this, the researchers conducted an experiment that had a sample of university students partake in two prisoner’s dilemma games with two other participants. At each round, players of the game are given the option to either cooperate with the other player or to defect in their own self-interest. The outcome that is the most beneficial for the two players occurs when both decide to cooperate, but each player is blind to the other’s decision. In the current study, the participants were awarded $3 at each round and given the opportunity to either keep the $3 or to transfer it to the other participant, in which case the reward would be doubled to $6.
Importantly, before playing the game, the students met with their opposing players and engaged in a ten-minute conversation with them. Following the game, all students completed a measure of psychopathy.
The researchers found that students with higher subclinical primary psychopathy strategically defected when met with players with low relational value — where low relational value referred to a lower quality interaction (the opponent interrupted them more frequently in their pre-game conversation) and a low expectation of future interaction (they and the opponent shared less common ground — e.g., sharing a hobby, a friend, a residence hall). Defecting to these low-value partners indicates a fitness advantage, given that low-value social partners have little to offer in terms of future benefits.
The study authors note that meeting opponents face-to-face before a one-shot social dilemma, such as the prisoner’s dilemma, typically enhances cooperation. Their findings suggest that, among people high in primary psychopathy, the effects of face-to-face interaction are dependent on what this interaction reveals about the other player. Without information suggesting high relational value — such as a high likelihood of future interaction with this person — face-to-face interaction seems not to influence people high in primary psychopathy.
Gervais and his team also point out that their study did not suggest any drawbacks to subclinical primary psychopathy. Notably, these participants were no more likely to be defected upon by other players and also no more likely to be predicted to defect.
The authors maintain that their study sheds light on the potential fitness advantages of subclinical psychopathy. “Although clinical psychopathy may prove adaptive only in social environments that facilitate the unconditional exploitation of others,” Gervais and colleagues say, “subclinical psychopathy may function more broadly in environments that present occasional opportunities for defection vis-à-vis particular low-value relationships.”
The study, “The strategy of psychopathy: primary psychopathic traits predict defection on low-value relationships”, was authored by Matthew M. Gervais, Michelle Kline, Mara Ludmer, Rachel George, and Joseph H. Manson.
