Objectives: The purpose of the investigation was to evaluate cortisol responsiveness in a naturalistic playground social setting. This ecologically valid design permits the careful investigation of social interaction in a play-based paradigm. In contrast to many studies of physiological responsivity, which inherently aim to solicit a stress response, the paradigm was designed to emulate a “real life” playground to determine whether such environments would be deemed physiologically stressful. The current study was designed to examine stress responsivity as measured by salivary cortisol comparing children with autism to neurotypical peers during a 20-min playground paradigm. In addition to traditional analysis based on examining frequency and duration of target behaviors, a transactional analysis of temporal and context based information was employed to more thoroughly capture the dynamic social exchanges.
Methods: The experiment involved sets of 3 children; a child with autism, a neurotypical child, and a neurotypical confederate. Participants included 45 prepubescent males between 8 to 12 years (21 with autism). Each twenty minute playground sequence included three children: a neurotypical child, a confederate and a child with high functioning autism. Recording was accomplished via four cameras, with combined coverage of all playground areas and lavalier microphones worn by each participant. Sound and video mixed records were subsequently coded using Noldus software. A sophisticated, detailed coding of interaction and play sequences was developed for this investigation. Four salivary samples were obtained: (S1) a baseline sample taken after arrival (~15 min acclimation) just prior to the playground peer interaction, (S2) post-play, (S3) 20-min post play, and (S4) 40-min post play.
Results: Repeated measures analysis of the cortisol values revealed a significant model
(χ²(4)=22.76, P<0.0005) that included time of measurement, diagnosis, and age as main effects and an interaction between diagnosis and age. Thus, older children with autism exhibited enhanced cortisol responsivity compared to their average afternoon cortisol levels, baseline, and compared to younger peers. Stress responsivity was associated with group play and reduced nonverbal social skills.
Conclusions: The enhanced cortisol response was observed in children who voluntarily engaged in interaction; thus, it does not support the notion of a response to social threat; rather, it appears to reflect attendant metabolic preparedness and enhanced arousal from engaging socially. The peer interaction paradigm resulted in a significant stress response in children with autism. Furthermore, distinct patterns emerged within the autism group based on developmental (older), biological (cortisol responder) and behavioral patterns (engaged in group social interaction). The data suggest that many children with autism mount measurable stress responses in relatively benign social situations, which appear to be a function of age and level of social engagement.