Remembering visual and linguistic common ground in shared history.

Successful communication requires speakers and listeners to refer to information in their common ground. Shared history is one of the bases for common ground, as information from a communicative episode in the past can be referred to in future communication. However, to draw upon shared history, communicative partners need to have an accurate memory record that they can refer to. The memory mechanism for shared history is poorly understood. The current study investigated the ways in which memory for shared history is prioritised. Two experiments presented a referential communication task followed by a surprise recognition memory task, with the former task serving as an episode of shared history. Experiment 1 revealed superior memory for information that was both seen in the communicators' common ground and referred to, followed by information that was seen but not referred to, and finally by information privileged to the participants. Experiment 2 provided a replication of Experiment 1 and further demonstrated that these co-presence effects are not dependent on the presence of a speaker with a different perspective to the participant.