The Repair of Speech Act Misunderstandings by Abductive Inference

During a conversation, agents can easily come to have different beliefs about the meaning or discourse role of some utterance. Participants normally rely on their expectations to determine whether the conversation is proceeding smoothly: if nothing unusual is detected, then understanding is presumed to occur. Conversely, when an agent says something that is inconsistent with another's expectations, then the other agent may change her interpretation of an earlier turn and direct her response to the reinterpretation, accomplishing what is known as a fourth-turn repair. Here we describe an abductive account of the interpretation of speech acts and the repair of speech act misunderstandings. Our discussion considers the kinds o fin formation that participants use to interpret an utterance, even if it is inconsistent with their beliefs. It also considers the information used to design repairs. We describe a mapping between the utterance-level forms (semantics) and discourse-level acts (pragmatics), and a relation between the discourse acts and the beliefs and intentions that they express. We specify for each discourse act, the acts that might be expected, if the hearer has understood the speaker correctly. We also describe our account of belief and intention, distinguishing the beliefs agents actually have from the ones they act as if they have when they perform a discourse act. To support repair, we model how misunderstandings can lead to unexpected actions and utterances and describe the processes of interpretation and repair. To illustrate the approach, we show how it accounts for an example repair.