Limitations/Future Directions
The current study has several limitations. Our pilot sample was
recruited from an ongoing longitudinal study, so feasibility may be
influenced by the familiar research setting or increased adherence to
habituation protocols at home. Still an unfamiliar team member
administered all procedures to ensure the social challenges were
comparable. The convenience sample also prevented concurrent measurement
of developmental level. Additionally, MRP task demands excluded children
using single or no words. Taken together, experimental design
modifications and larger sample sizes may elucidate how RSA relates to
externalizing behavior in a more representative sample of autistic
children.
Future studies may also benefit from collecting additional physiological
measures. While there is no “gold-standard” method for computing RSA,
methods are differentially impacted by artifact (Larsen et al., 2010;
Lewis et al., 2012) and by measuring RSA using obtained respiration
versus normative respiration levels (Graziano & Derefinko, 2013).
Studies collecting both ECG and respiration could directly test the
impact of different RSA computation methods. Furthermore, given RSA and
behavioral outcomes may be dynamically impacted by co-occurring
sympathetic activity (Fenning et al., 2019), obtaining measures of PEP
or galvanic skin response could further elucidate relations between
physiological response and externalizing behavior.