Conclusion
The current study provides preliminary support for the use of a domain-specific approach to examining RSA-R in autistic children. By evaluating physiological responses during social, cognitive, emotional, and sensory challenges, we can more precisely characterize how autistic children self-regulate across contexts and identify what kinds of physiological reactivity are most relevant for externalizing behavior for autistic children. The current study is the first to find a relationship between socially induced RSA-R and externalizing behavior among young autistic children. Further, the feasibility of the current protocol is encouraging for replication in a larger sample. Understanding the physiological mechanisms underlying externalizing behaviors supports the development of objective methods to identify which children may respond best to behavioral support or intervention to optimize behavioral outcomes.