A study at Leicester University and Exeter University has found that the traditional view that decision makers only act in their own interest is incorrect – in some instances, decision makers act in the best interest of their team, often at their own expense. Classical game theory predicts that people act out of their individual self-interest while team reasoning theory suggests that people look after the interest of their team, not always their own selfish interests. Their findings show that team reasoning predicts decision making more powerfully than orthodox game theory in some games.

Specifically, their findings from two experiments: lifelike vignettes (Experiment 1) and abstract games (Experiment 2) with certain structural properties provide evidence in support of collective preferences and team reasoning. Most players preferred team-reasoning strategies over the unique Nash equilibriua strategies supported by traditional game theory.

In both the games studies, the pair of players who followed team-reasoning strategies received higher payoffs than those who chose Nash equilibria. In all cases, a player motivated by individualistic payoff maximization could have obtained a higher payoff by choosing differently.

In traditional game theory, a strategy is dominant if it earns a player a larger payoff than any other, regardless of what other players do.

The experimental design can be found here.