A Social Motivation and Competency Scale for ASD: Confirmatory Factor Analytic Structure and Measurement Invariance of Quantitative Socialization Traits

Background: The constructs of social motivation and competency are primary considerations when attempting to understand and target the interpersonal vulnerabilities inherent in autism spectrum disorder (ASD). Social motivation is particularly pivotal, as the desire to engage provides the experience necessary to increase social competencies and can yield favorable social experiences to further increase motivation (Chevallier et al., 2012). To successfully implement social intervention efforts, it is critical to understand each participant’s unique profile of social motivation and associated competencies (Vernon et al., 2016). To date, qualitative judgements of these constructs have been the default strategy for individualizing autism intervention approaches; no measurement scale currently exists that attempts to quantify these attributes in a single instrument.

Objectives: The objective of the current study is to provide initial validation of a Social Motivation and Competency Scale (SMCS) as a parent- and self-report measure designed for youth and young adults with ASD through the use of confirmatory factor analysis.

Methods: The Social Motivation and Competency Scale (SMCS) is a 26-item measure that assesses an individual’s motivation and competency in social communication situations. Separate parent- and self-report versions were developed with identical item content. Items pertaining to comfort in social interaction, conversation skill use, empathy, friendships, appropriate behavior, social contact, and social interest are rated on 1-5 Likert scales. A sample of 200 participants (108 teens and adults with ASD and 92 parents) completed the SMCS as part of a larger intervention study. Confirmatory factor analysis, internal consistency, model fit indices, factor loadings, and between-factor correlation matrix were conducted to determine construct validity.

Results: Results of the CFA on the total sample indicated that the two-factor model showed adequate fit across indices with the exception of CFI where fit was approaching adequacy (CFI=.896). Factor loadings for both factors were adequate and statistically significant (p < .001) with all loadings >.48. Comparing the configural confirmatory factor analysis model to the model with metric invariance across groups, there was a significant increase in model misfit (Δχ2 (474, N=200)=928.12, p<.001) based on chi-square difference test, suggesting that the factor loadings are not equivalent across groups. We did not establish invariance across the child and parent groups.

Conclusions: We found that the two-factor structure of the SMCS proposed by the creators had adequate fit for the overall sample and child group. Being able to easily measure these two constructs has important future implications, as being able to understand baseline levels of these characteristics can help inform which specific areas of social skill to target for optimal outcomes. Although we failed to establish invariance between child- and parent-reports, these results are not surprising when theoretically examining why individuals with ASD and their caregivers might view these constructs differently. Future directions will examine the factor structure of the SMCS in a larger population and can also serve to collaborate with other researchers to identify indicators that more sensitively measure motivation and competency across raters so that accurate measures of these domains can be established and compared.