Proceedings of the Annual Meeting of the Cognitive Science Society

Language is widely assumed to be a well designed tool for re-liably communicating propositional information between peo-ple. This suggests that its users should be sensitive to failuresof communication, such as utterances that are blatantly inco-herent with respect to an ongoing conversation. We presentexperimental work suggesting that, in fact, people are surpris-ingly tolerant of conversational incoherence. In two previousstudies, participants engaged in instant-messaging conversa-tions that were either repeatedly crossed with other conversa-tions or had lines inserted into them that deliberately contra-dicted available information. In both cases, a substantial pro-portion of participants failed to notice. In a new study, confed-erates inserted unexpected, nonsensical lines into face-to-faceconversations. The majority of participants failed to notice.We argue these findings suggest that we should be wary ofmodeling spontaneous communication in terms of faithful in-formation transmission, or language as a well designed tool forthat purpose.