Are extraverts or introverts more cooperative? It depends on the situation

Our achievements as a species owe a debt to our willingness to cooperate. But we all vary in how we solve the social dilemma – whether in any given situation we choose to favour self-interest or cooperation. This issue has long fascinated researchers, who delight in testing people's choices in hypothetical setups involving prisoners' loyalty to each other or the sharing of community resources. But these setups have struggled to give us a clear picture of how personality tips people one way or another: for example, are extraverts more cooperative by instinct than introverts?

A new paper published in Philosophical Transactions B suggests that we need to use the right frame: the context surrounding a dilemma affects how it's tackled by different personality types. Extraverts act more exploitatively in social dilemmas than introverts, the research shows, but only when they think they can get away with it.

The 177 undergraduate participants tackled a setup called the Public Goods Game, where they had to decide whether to hang onto their tokens or put them into a public pot, where they would swell in value before being shared between the game's four players, collaborating over a computer network. If everyone invests, each player is better off, but such collaboration is not guaranteed so a token in the hand is still arguably worth more to a player than his or her share of the future public pot. Extra realism came from the fact that each player's end-of-game tally of tokens was converted into real money once the study was over.

Kari Britt Schroeder and her colleagues found that over ten rounds of this game, extraverts were more likely to hold back tokens for themselves. But then the researchers shifted the rules so that now following each of the next ten rounds participants got to see how everyone else had invested during that round, and they also had the chance to assign other players negative tokens, which cost the giver one token but taxed the recipient three. In this punishment stage, extraverts were more generous than introverts, tending to put more of their tokens into the public pot.

The researchers expected to find these effects of personality on cooperation. Extraversion is known to make gaining rewards more appealing, creating a temptation to free-ride even though it may not be morally "right". But when the possibility of punishments kicks in, free-riding loses its appeal, and extraverts see more reward in banding together. Or perhaps the disincentive is the loss of social standing implied by being fined by others, as extraverts are particularly keen on positive attention. Regardless of the cause, the experiment shows that the larger context totally reconfigures the effect personality has on cooperation.

Clearly the same goes for real life. Most social dilemmas don't take place in a vacuum; they require a context, often an institution armed with more or less power to discipline anti-social behaviour. You can't be punished for selfish behaviour in the park, but you can be at work – unless, maybe, your father is the boss. So researching social dilemmas with more consideration of this institutional weight will hopefully be the key to a better understanding of who in a given context is likely to be more prone to selfish temptation … and perhaps help us figure out a way forward through the social dilemmas that the 21st century poses to us.

References

Schroeder, K., Nettle, D., & McElreath, R. (2015). Interactions between personality and institutions in cooperative behaviour in humans Philosophical Transactions of the Royal Society B: Biological Sciences, 370 (1683) DOI: 10.1098/rstb.2015.0011