Development of the Stanford Social Dimensions Scale (SSDS): Initial Validation in Autism Spectrum Disorder

Background: Social motivation theory has been put forward as a useful framework for understanding the emergence of social impairments in autism spectrum disorder (ASD), highlighting deficits in social motivation as a potentially important target for treatments. However, despite the noted prominence of the construct, there is a paucity of instruments specifically designed to capture individual differences in social motivation.

Objectives: To provide an initial validation of a newly developed instrument—the Stanford Social Dimensions Scale (SSDS), designed specifically to capture individual differences in different components of social motivation as well as along other distinct dimensions of social functioning in a quantitative and comprehensive manner.

Methods: Parents of 167 individuals with ASD (age range: 2-17 years) completed the SSDS, the Social Responsiveness Scale (SRS-2) and the Child Behavior Checklist (CBCL). Data on children’s verbal and non-verbal intellectual functioning (VIQ, NVIQ) was also collected.

Results: Exploratory Structural Equation Modelling indicated that a five-factor model provided adequate to excellent fit to the data (comparative fit index [CFI]= .940, Tucker Lewis Index [TLI]= .919, root mean square error of approximation [RMSEA]= .048 [90% CI: .039, .056], standardized root mean square residual [SRMR]= .038). The identified five factors were interpreted as Social Motivation, Social Affiliation, Expressive Social Communication, Social Reception and Unusual Approach. Internal consistency was in the good to excellent range as indicated by Composite Reliability scores of ≥ .72. Convergent and divergent validity across all SSDS scales was strong as indexed by the pattern of correlations with relevant SRS-2 and CBCL domains and with NVIQ and VIQ scores.

Conclusions: Ability to capture this phenotypic heterogeneity and identify individual patterns of strength and weakness across different domains of social functioning is an essential step in informing personalized intervention and case management plans as well as prediction of long-term outcomes. Our findings provide initial validation of a new scale designed to comprehensively capture individual differences in social motivation and other key social dimensions in ASD.