BACKGROUND: Definite references signal a speaker's belief that a listener can uniquely identify the referent (e.g., the dog, as the only dog among a group of animals). Clark's (1992) collaborative referencing model provides a way to examine the speaker's display of confidence that his/her reference will be understood by the listener without further clarification. We previously found that amnesia participants, as directors in a barrier task with a familiar partner, used referencing forms that displayed less confidence than forms used by comparison participants. If this is an interactional consequence of managing the memory impairment (as opposed to a language deficit), we should also expect a decrease in definite referencing by their partners. AIMS: To examine the use of definite references by healthy non-brain-damaged participants when speaking to their memory-impaired partner during repeated trials of a barrier task. METHODS #ENTITYSTARTX00026; PROCEDURES: We replicated our previous work with 11 of the same participant pairs-6 individuals with hippocampal amnesia and 5 comparison participants-each of whom was paired with a familiar partner of their choosing. Focusing on the productions of the partners (i.e., partners became directors) we (1) coded referential expressions as definite or indefinite; (2) tracked changes in the use of indefinite and definite references across trials; and (3) compared data to previous analyses (when amnesia participants were directors). OUTCOMES #ENTITYSTARTX00026; RESULTS: The productions of comparison pairs were overwhelming definite (95%, 1359). In sharp contrast, partners of the amnesia participants used a definite initiating reference less than half the time (48%, 825), when speaking to their memory-impaired partner and used definite references that signalled a lack of confidence more often and across more trials. CONCLUSIONS: These findings support the assumption that disruptions in language-and-memory-in-use are not limited to the productions of the individuals with amnesia, but rather extend to the discourse of their communication partners. Observing disruptions in the use of definite references of individuals with intact language and declarative memory, when communicating with their partner with amnesia, points to the complex interaction of memory and language. Even when attention is paid to grammatical forms, the decisions are never linguistic alone.