Proceedings of the Annual Meeting of the Cognitive Science Society

Young children make systematic mistakes when reasoning about what other agents know and believe -- mature mental state reasoning emerges around late childhood. We describe a novel class of errors that adult reasoners make when considering information about the mental states of others. Participants in two studies reasoned about common conditional reasoning inferences couched in terms of an agent’s knowledge or belief, e.g., Alia knows that if it’s rainy then the café is closed; It’ s rainy. What follows? They generated their responses using a novel sentence construction interface. Many participants spontaneously generated responses such as, Alia knows that the café is closed. This pattern reflects an “omniscience” error, i.e., one in which reasoners erroneously impute knowledge of a deductive consequence to an agent. We discuss the results in the context of recent proposals on epistemic inference.