Socially smart software agents entice people to use higher-order theory of mind in the Mod game

In social settings, people often need to reason about unobservable mental content of other people, such as their beliefs, goals, or intentions. This ability helps them to understand, to predict, and even to influence the behavior of others. People can take this ability further by applying it recursively. For example, they use second-order theory of mind to reason about the way others use theory of mind, as in ‘Alice believes that Bob does not know about the surprise party’. However, empirical evidence so far suggests that people do not spontaneously use higher-order theory of mind in strategic games. Previous agent-based modeling simulations also suggest that the ability to recursively apply theory of mind may be especially effective in competitive settings. In this paper, we use a combination of computational agents and Bayesian model selection to determine to what extent people make use of higherorder theory of mind reasoning in a particular competitive game, the Mod game, which can be seen as a much larger variant of the well-known rock-paper-scissors game. We let participants play the competitive Mod game against computational theory of mind agents. We find that people adapt their level of theory of mind to that of their software opponent. Surprisingly, knowingly playing against second- and third-order theory of mind agents entices human participants to apply up to fourth-order theory of mind themselves, thereby improving their results in the Mod game. This phenomenon contrasts with earlier experiments about other strategic oneshot and sequential games, in which human players only displayed lower orders of theory of mind