Great apes show altercentric influences when confronted with conflicting beliefs

Humans' beliefs are automatically impacted by others' beliefs. This so-called altercentric influence indicates that we rely on automated mental simulation to track others' beliefs. It is unclear whether nonhuman great apes rely on similar cognitive processes. In this study, we used a novel search task where nonhuman apes could dig for buried rewards in a trough after seeing an experimenter hiding them. The task was designed as a game between a human agent and an ape participant. There were two hiding locations of the reward in the trough, and the participant always had full visual access to the original hiding of the reward and its relocation to another location. The human agent, however, only saw the relocation in the true belief condition but missed it in the false belief condition. Our results show that others' (conflicting) beliefs seem to impact nonhuman great apes’ information encoding by showing that apes searched for the reward closer to the first hiding location when the agent believed it to be there (false belief condition) compared with when the agent knew the reward was at the new location (true belief condition). Moreover, humans and nonhuman great apes undergo similar ontogeny with a stronger altercentric influence in younger individuals. The present study provided additional evidence that nonhuman great apes possess basic abilities to track the beliefs of other individuals, indicating that automatic belief simulation might be part of the shared evolutionary history of all great apes. • Great apes can track a human bystander's beliefs. • Altercentrism is not unique to humans but is anchored in great ape cognition. • Altercentric influences develop similarly in humans and great apes. • Automatic belief-simulation sufficiently explains altercentric influences.