Core Intuitions of Psychological Non-Contradiction: Infants Assume That Individual Agents Act and Communicate Coherently

Abstract Humans generally posit that contrary mental states are unlikely to co-exist within a single mind. We tested the early ontogeny of this assumption in two domains: action and communication. Studies 1A and 1B tested whether 9-month-old infants assume that agents act coherently. Infants watched interactions between two hands whose owner(s) were invisible. In the contrary goals condition, the hand performed contrary actions—one hand reached for an object while the other impeded it. Later, during test trials, infants learned that the hands belonged to one or two people. Looking-time patterns across the contrary goals and a baseline conditions indicated that clear goal conflict led infants to infer two agents, suggesting they viewed it as unlikely for a single person to thwart their own goal. Study 2 tested whether infants assume communicative coherence, testing whether they assume that a single informant is unlikely to entertain and communicate conflicting information while two informants might do so. Informants pointed to indicate a toy’s location to 15-month-olds. When two different informants each pointed to a different place, infants did not follow one pointing gesture more than the other. However, when a single informant pointed successively to two locations, infants followed the second gesture, implying they viewed it as an updated, not contradictory, message. Thus, infants assumed that a single informant is unlikely to contradict themselves (i.e., by asserting that a toy is simultaneously in two locations). These findings reveal an early-emerging assumption of psychological coherence in infants’ representation of other minds, across both action and communication contexts.