Diagnostic status influences rapport and communicative behaviours in dyadic interactions between autistic and non-autistic people.

A growing body of research suggests that the behaviours and experiences of autistic and non-autistic people are influenced by whether they are interacting with someone of the same or different diagnostic status. However, little is known about the relationship between these behaviours and the experiences of rapport in matched and mixed neurotype dyads. Using the Actor-Partner Interdependence Model, our pre-registered analyses examine how participants' and their partners' diagnostic statuses influence linguistic, behavioural, and kinematic indices, and how these relate to feelings of rapport among autistic and (n = 57; 17 self-diagnosed) non-autistic (n = 51) participants interacting within autistic (n = 20), non-autistic (n = 17), and mixed autistic-non-autistic (n = 17) dyads. We found that autistic participants reported lower rapport regardless of their partner's diagnostic status, though awareness of their partner's diagnostic status had a moderating effect. We observed a linguistic difference, autistic participants produced longer mean utterance lengths, these and other behavioural or kinematic indices did not mediate the relationship between diagnostic status and rapport across neurotypes. The current work highlights the need for a nuanced understanding of communication dynamics in autism.