Referential Form and Memory for the Discourse History.

The way we refer to things in the world is shaped by the immediate physical context as well as the discourse history. But what part of the discourse history is relevant to language use in the present? In four experiments, we combine the study of task-based conversation with measures of recognition memory to examine the role of physical contextual cues that shape what speakers perceive to be a part of the relevant discourse history. Our studies leverage the differentiation effect, a phenomenon in which speakers are more likely to use a modified expression to refer to an object (e.g., dotted sock) if they had previously described a similar object (e.g., striped sock) than when they had not described a similar object. Two physical cues-the background that framed the to-be-described pictures and the position of the pictures in the display-were manipulated to alter perceptions about the relevant discourse context. We measured the rate with which speakers modify referring expressions to differentiate current from past referents. Recognition memory measures following the conversation probed what was and was not remembered about past discourse referents and contexts. Analysis of modification rates indicated that these contextual grouping cues shaped perceptions about the relevant discourse context. The contextual cues did not affect memory for the referents, but the memory for past referents was better for speakers than for listeners. Our findings show that perceptions about the relevant discourse history are a key determinant of how language is used in the moment but also that conversational partners form asymmetric representations of the discourse history.