Memory activation and retrieval strategy in lexical alignment: Comparing the ACT–R model of human and computer interlocutors

During conversations, speakers tend to reuse the lexical expressions of their interlocutors. This is called “lexical alignment,” and it facilitates the listener’s understanding of the speaker’s intention. Branigan (2011) has shown that this tendency increases when speakers believe that their partner is a computer agent rather than a human. Memory activation for the expressions used by the interlocutors and the strategy preference whereby speakers attempt to use their partners’ expressions rather than those that first come to mind have been shown to be the causes of lexical alignment. For this study, we constructed an ACT–R model for which we could adjust the parameter values related to these two features. Through parameter adjustment, we simulated lexical alignment with both human and computer agents. For both partner conditions, additional activation was added to the knowledge of the partners’ expressions. The computer–partner model preferred trying to retrieve the partners’ expression rather than using the knowledge that had a strong association with the stimulus and was easy to retrieve. In contrast, the human–partner model had no specific preference; that is, it displayed equal utility for both. A comparison of these parameter values revealed that the computer–partner model preferred to retrieve the partner’s knowledge; in addition, it also kept the knowledge’s activation sufficiently high so that it could be available for a longer duration.