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Taking a More Sophisticated Look at Human Beings

When it comes to social dilemmas, there are four types of people, experimental economists say.

By Nathan Collins


(Photo: Oiluj Samall Zeid/Flickr)

Are people fundamentally selfish, or are they cooperators? Actually, it’s kind of an odd question—after all, why are those the only options? The answer is that those options are derived in large part from philosophy and classical economic theory, rather than data. In a new paper, researchers have flipped the script, using observations of simple social situations to show that optimism, pessimism, envy, and trust, rather than selfishness and sacrifice, are the basic ingredients of our behavior.

That conclusion advances wider “efforts toward the identification of basic behavioral phenotypes,” or categories of behavior, and the results could be usefully applied in social science, policy, and business, Julia Poncela-Casasnovas and her colleagues write in Science Advances.

Classical economic theory has something of a bad reputation these days, and not without reason. For one thing, most economic theory assumes people are rational, in the sense that they are strategic and maximize their payoffs in all that they do. The list of objections to that approach is long and well-documented, but there’s a counter objection—amid a slew of objections and anecdotes, there’s little in the way of a cohesive alternative theory.

Optimism, pessimism, envy, and trust are the basic ingredients of our behavior.

Poncela-Casasnovas and her colleagues’ experiments are, they hope, a step toward such a theory. Their idea was to put ordinary people in simple social situations with economic tradeoffs, observe how those people act, and then construct a data-driven classification of their behavior.

To that end, the researchers recruited 541 people at a fair in Barcelona and paired them up to play a series of 13 to 18 games for points which they could exchange for lottery tickets. Each player could choose one of two actions, corresponding to whether they chose to cooperate or not. Although the rewards were chosen at random, the games typically imposed some sort of tradeoff—for example, mutual cooperation might produce a good payoff for both players, but one player could score more points by taking advantage of another’s cooperation. (“Games,” by the way, is economist-speak for situations where a person’s payoffs depend on all the players’ actions. It’s a broad definition: Poker is a game, but so is nuclear war.)

The question is not just how people play these games—there are hundreds of research papers on that—but instead whether people fall into behavioral types that explain their behavior across different games. Using standard statistical methods, the researchers identified four such player types: optimists (20 percent), who always go for the highest payoff, hoping the other player will coordinate to achieve that goal; pessimists (30 percent), who act according to the opposite assumption; the envious (21 percent), who try to score more points than their partners; and the trustful (17 percent), who always cooperate. The remaining 12 percent appeared to make their choices completely at random.

Those results don’t yet add up to anything like a theory of human behavior, but they do “open the door to making relevant advances in a number of directions,” the authors write. In particular, the researchers hope their results will help explain behavior in other simple games, and aid those hoping to understand how people may respond to new policy initiatives.