This study was a preliminary investigation of parasympathetic nervous system (PNS) functioning in children with disturbances in sensory processing. The specific aims of this study were to (1) provide preliminary data about group differences in parasympathetic functions, as measured by the vagal tone index, between children with disturbances in sensory processing and those without; (2) determine effect size and power needed for future studies; and (3) to lay the foundation for further examination of the relations of parasympathetic functioning and functional behavior in children with disturbances in sensory processing.
Participants were 15 children, nine with disturbances in sensory processing and six typically developing children. Heart period data were continuously collected for a 2-minute baseline and during administration of the 15-minute Sensory Challenge Protocol, a unique laboratory protocol designed to measure sensory reactivity (Miller, Reisman, McIntosh, & Simon, 2001). Groups were compared on vagal tone index, heart period, and heart rate using two-tailed, independent sample t tests.
Children with disturbances in sensory processing had significantly lower vagal tone than the typically developing sample (t(13) = 2.4, p = .05). Statistical power analysis indicated that, for future studies, a sample size of 20 in each group would yield adequate statistical power. Although the number of subjects in this pilot study is small, the results from this study support further investigations of parasympathetic functions and functional behavior in children with disturbances in sensory processing.