Compensating for an Inattentive Audience.

The common ground that conversational partners share is thought to form the basic context for language use. According to the classic view, inferences about common ground, or mutual knowledge, are guided by beliefs about the physical, cognitive, and attentional states of one's communicative partners. Here, we provide a first test of the attention assumption for common ground, the proposal that common ground for a co-present entity-such as an object or an utterance-can only be formed if a person has evidence that his or her partner has also attended to it. In three experiments, a participant speaker and two partners learned names for novel monster pictures as a group. The speaker was then asked to describe the monsters to each partner separately in a referential communication task. The critical manipulation was the (in)attentiveness of one partner at different points in the study. Analysis of the speaker's referring expressions revealed that speakers assumed their partner shared common ground for the monster names only when that partner exhibited engaged attention as the names were learned. These findings provide key and novel support for the classic proposal that formation of common ground critically depends on assumptions about the attentional state of one's conversational partner.