In psycholinguistics, the collaborative model (or conversational model) is a theory for explaining how speaking and understanding work in conversation, specifically how people in conversation coordinate to determine definite references. The model was initially proposed in 1986 by psycholinguists Herb Clark and Deanna Wilkes-Gibbs. It asserts that conversation partners must act collaboratively to reach a mutual understanding – i.e. the speaker must tailor their utterances to better suit the listener, and the listener must indicate to the speaker that they have understood.