Representation of others' synchronous and asynchronous sentences interferes with sentence production.

In dialogue, people represent each other's utterances to take turns and communicate successfully. In previous work, speakers who were naming single pictures or picture pairs represented whether another speaker was engaged in the same task (vs a different or no task) concurrently but did not represent in detail the content of the other speaker's utterance. Here, we investigate the co-representation of whole sentences. In three experiments, pairs of speakers imagined each other producing active or passive descriptions of transitive events. Speakers took longer to begin speaking when they believed their partner was also preparing to speak, compared to when they did not. Interference occurred when speakers believed their partners were preparing to speak at the same time as them (synchronous production and co-representation; Experiment 1), and also when speakers believed that their partner would speak only after them (asynchronous production and co-representation; Experiments 2a and 2b). However, interference was generally no greater when speakers believed their partner was preparing a different compared to a similar utterance, providing no consistent evidence that speakers represented what their partners were preparing to say. Taken together, these findings indicate that speakers can represent another's intention to speak even as they are themselves preparing to speak, but that such representation tends to lack detail.