Abstract
BACKGROUND: Autism is considered to entail a social impairment whereby autistic people experience difficulty interpreting others' mental states. However, recent research has shown that nonautistic people also have difficulty understanding the mental states of autistic people. This mismatch of understanding may explain lower rapport in interactions between autistic and nonautistic people. As mental states can be expressed externally through socially normed signals, it is important to investigate the role of such signals in autistic, nonautistic, and mixed interactions. This study explores variability in two social signals between autistic, nonautistic, and mixed interactions, and how their use may affect rapport within interactions. METHODS: Videos from a previous study of autistic, nonautistic, and mixed pair interactions in a diffusion chain context in which participants were aware of others' diagnostic status were video coded for mutual gaze and backchanneling as candidate indicators of interactional rapport. RESULTS: Although use of mutual gaze and backchanneling was lower in mixed pairs than in nonautistic pairs, corresponding to lower ratings of interactional rapport, less backchanneling in autistic pairs of both nonverbal and verbal subtypes corresponded to higher ratings of rapport. CONCLUSIONS: We observed differences in the use of candidate rapport markers between autistic, mixed, and nonautistic interactions, which did not map onto patterns of rapport scores, suggesting differences in reliance on these cues between autistic and nonautistic people. These results suggest that visible markers of rapport may vary by neurotype or pairing and give clues to inform future investigations of autistic interaction.