Social motor synchrony and interactive rapport in autistic, non-autistic, and mixed-neurotype dyads

In non-autistic populations, social motor synchrony during interactions is linked to increased interpersonal rapport – a friendly connection marked by mutual understanding and ease of communication. Previous research indicates autistic individuals show lower social motor synchrony in interactions with both autistic and non-autistic partners. However, it is unclear if this affects rapport, as synchrony’s role in social communication may differ for autistic individuals. The study had three aims: to replicate and extend previous findings of reduced social motor synchrony in dyads with at least one autistic person; second, to examine the relationship between synchrony and rapport in autistic ( n = 12), non-autistic ( n = 17), and mixed dyads ( n = 14); and third, to investigate reliance on motor synchrony for achieving rapport among autistic and non-autistic participants. We found no evidence that dyads with at least one autistic person have less social motor synchrony than dyads without an autistic person. However, we found that social motor synchrony positively affects rapport more in non-autistic dyads than in autistic dyads. Participant-level analysis indicated that non-autistic individuals require higher social motor synchrony levels to achieve high rapport levels than autistic individuals. These results suggest that non-autistic individuals may emphasise movement synchrony as a key component of successful social interaction. Lay abstract During social interactions, people often mirror each other’s movements and gestures, a process called synchrony. This synchrony helps foster a sense of connection, understanding, and ease in communication. While research suggests that autistic people may show less synchrony in their movements compared to non-autistic people, the implications of this difference for building rapport remain unclear. Specifically, it is unknown whether synchrony plays a similar role in rapport-building for autistic individuals as it does for non-autistic individuals, particularly in interactions with autistic versus non-autistic partners. This study had three goals to investigate whether synchrony is lower in conversations involving at least one autistic person; to explore the relationship between synchrony and rapport; and to compare how much autistic and non-autistic people rely on synchrony to feel connected. The findings suggest that while synchrony positively influences rapport more strongly in non-autistic interactions, autistic individuals may rely less on synchrony for rapport. These results highlight differences in how social connection is built, offering deeper insight into social interactions for autistic and non-autistic people.