Pretending not to know reveals a capacity for model-based self-simulation

Feigning ignorance is crucial in contexts as diverse as diplomacy, warcraft and personal relationships, each demanding strategic concealment of information. Successful ‘epistemic pretense’ requires one to anticipate how one would behave without a given piece of knowledge, and act according to that counterfactual knowledge state. Here, two game-based experiments reveal a striking capacity to simulate decision-making under counterfactual knowledge. 1001 English-speaking adults saw the full solution to a game (all ship locations in Battleship, or the hidden word in Hangman) but then attempted to play as though they never had this information. Impressively, they mimicked broad and subtle patterns of ordinary play. While peers were completely unable to detect pretense, computational modeling uncovered traces of ‘over-acting’ in pretenders’ decisions, suggesting a schematic simulation of their minds. Opening up a new approach to studying self-simulation, our results reveal intricate metacognitive knowledge about decision-making, drawn from a rich—but simplified—internal model of cognition.