Date Presented 03/28/20
This paper uses confirmatory factor analysis to assess the hypothesis that tactile defensiveness in children with ASD can be separated into two distinct factors based on whether stimulation is initiated by the child or by external sources. Model fit was good using standard fit measures, suggesting that the level of control over stimuli should be considered when addressing functioning in daily life.
Primary Author and Speaker: Kathryn Williams
Contributing Authors: John Sideris, Grace Baranek
PURPOSE: Occupational therapy practitioners (OTPs) often work closely with children with Autism Spectrum Disorder (ASD) to address tactile defensiveness (TD; Ayres, 1964). Currently, TD includes responses to child-initiated stimuli and reactions to externally-driven stimuli that are unpredictable and uncontrollable. The purpose of this study is to test the hypothesis that these two factors are distinct types of TD, in order to provide empirical evidence that supports practitioners when deciding on interventions.
DESIGN: TD was separated into two distinct subgroups (DEF-internal and DEF-external) based on whether stimuli were internally or externally controlled. The sample included 120 children with ASD (mean age(sd) in years: 5.53(2.28)). Children were excluded if they were diagnosed with fragile X syndrome, tuberous sclerosis, uncontrolled seizure disorder, cerebral palsy, mental age <6 months, or failure on the vision or hearing screenings.
METHOD: The Tactile Defensiveness and Discrimination Test-Revised (TDDT-R; Baranek, 2009) is a 20-minute, semi-structured play-based assessment of tactile function. A confirmatory factor analysis was conducted on pre-determined items on the TDDT-R in order to evaluate the associations between item-level scores and underlying latent constructs of DEF-internal and DEF-external. Data were analyzed using Mplus (Muthén & Muthén, 2010); the model was fit under maximum likelihood estimation and the model was standardized such that factor means were fixed to zero and factor variances were fixed to one.
RESULTS: Model fit was good using standard fit measures of RMSEA (0.046) and CFI/TLI (0.973). The normed chi-square value also suggested good model fit (345.6(274)**). The correlation between DEF-internal and DEF-external was 0.54. No post hoc adjustments were made to the model. Results support the hypothesis for two related but distinct factors of TD based on whether stimulation is internally versus externally controlled.
CONCLUSION: OTPs often work closely with children with ASD to address sensory modulation difficulties in multiple sensory domains throughout development, including TD. This study impacts occupational therapy practice because it suggests the need to consider the level of control a child with ASD has over contextual stimuli when addressing adaptive functioning in daily life. Future research is warranted to better understand how these factors relate to other aspects affiliated with ASD such as anxiety.
References
Ayres, A. J. (1964). Tactile functions: Their relation to hyperactive and perceptual motor behavior. American Journal of Occupational Therapy, 18, 6–11.
Baranek, G.T. (2009). Sensory experiences questionnaire version 3.0. Unpublished manuscript.
Muthén, L.K., Muthén, B.O. (2010). Mplus user’s guide. 6. Los Angeles.
