Dyadic Physiological Linkage As a New Measure of Social Reciprocity in ASD

Background: Although early intervention is preferable, little is known about interventions to support the growing population of adults with Autism Spectrum Disorder (ASD) (Mandell,2013; Warren et al.,2011). One core ASD impairment area involves social reciprocity. Because of the impact of social reciprocity impairments, further research on objective measures of social reciprocity can clarify its role in ASD and provide novel ways to assess response to treatment of social impairments.

Objectives: To address these issues, we examined physiological linkage (PL) as a form of social reciprocity. PL refers to coordinated physiological responses between one or more partners in a social interaction. PL is couched in several important constructs in psychology, such as affect matching, mirroring, perspective-taking, and joint attention. As such, we propose that PL encompasses the broader underlying construct of social reciprocity, and thus provides a unique, objective, and quantifiable measure that can be used to further our understanding of social competence in both typical and atypical development in naturalistic interaction contexts.

Methods: In the current study, twenty-six typically developing (TD) dyads and three ASD/TD dyads participated in a social task where each person discussed happy or sad events while the other listened and the cardiac inter-beat interval for each person was monitored. The second-to-second change in the logarithm of the IBI was calculated for each person in each dyad and a bivariate time-series model was specified and estimated, allowing for subject-specific intercepts and gender-specific dynamic lag structures.

Results: In general, for the TD dyads, the findings showed a small but highly significant linkage effect (p<0.00005) for both male and female dyads. The effect was stronger for female dyads, however, and persisted to a lag of 4 seconds. For males, the effect was weaker and only significant at a lag of 1 second. For the ASD/TD mixed dyads (2 female and 1 male), the results showed no significant linkage effects for either the ASD or TD subject, and the effect sizes for the results were small. In particular, the null hypothesis of no linkage effect on the ASD person could be rejected only with p>0.184 and 0.624 (for the females and the male, respectively); the analogous rejection p-values were 0.332 and 0.624 for the TD person. That is, the ASD person’s log IBI did not appear to vary in response to the TD person’s log IBI, and vice versa; and the TD person’s log IBI did not appear to vary in response to the ASD person’s log IBI either.

Conclusions: This study helps to elucidate that TD dyads may have a linkage effect, while ASD/TD dyads do not exhibit the same linkage. While the number of dyads analyzed is small, this preliminary study is one of the first to demonstrate differences in how individuals with and without ASD engage in social reciprocity through PL.