Author: Lai, Yuen Yi Cynthia
Title: A study of behavioral and autonomic responses in autistic children with sensory processing difficulty
Degree: Ph.D.
Year: 2013
Subject: Autism in children.
Sensory integration dysfunction in children.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Rehabilitation Sciences
Pages: xviii, 264 p. : ill. (some col.) ; 30 cm.
Language: English
Abstract: This thesis proposed to apply the concepts of allostasis and self-regulation to redefining the difficulties encountered by children with Autism Spectrum Disorders (ASD) in processing sensory stimulations. This thesis consisted of two phases of study. Phase 1 of the study validated the two major forms (Home and Main Classroom) of the Sensory Processing Measure-Hong Kong Chinese version (SPMHKC) in 542 and in 325 Chinese, typically developing (TD) children, respectively. The internal consistency of the SPMHKC was good. Four out of nine Home scales and eight out of nine Main Classroom scales had Cronbach's alpha values greater than or equal to .80. In addition, three Home scale and one Main Classroom scale had Cronbach's alpha values of between .70 and .80. The testretest reliability of the SPMHKC was good to excellent. The intraclass correlation coefficients of the Home and Main Classroom Forms scales ranged from .70 to .95 and .82 to .98, respectively. The discriminant validity of the SPMHKC was excellent. For both the Home Form and the Main Classroom Form, the ASD group had significantly higher (more undesirable) scores (all p < .001) than their non-ASD peers. However, the correlation of behavior of the Hong Kong Chinese children toward sensory events across settings was found to be low or not statistically significant, demonstrating an even lower correlation than that of the U.S. population. In Phase 2 of the study, the behaviors of 26 TD and 30 ASD participants were measured with the SPMHKC, and a sensory experiment (SE) was adopted for measuring their autonomic responses in passive and active sensory processing. The SE had three blocks of sensory tasks (P1auditory; P2visual; and P3tactile), one block of cognitive tasks (P4anticipatory), and four interleaved resting periods. Heart rate variability (HRV) was measured; SD1 and the SD1/SD2 ratio of the Poincare Plot reflected parasympathetic functioning and autonomic balance, respectively. This study found that the baseline SD1 and the SD1/SD2 ratio captured at the initial resting condition (R0) of the ASD group were significantly lower than those of the TD group (p = .001 and p = .007, respectively). For passive sensory processing, the interaction effect between Condition (R0, P1, P2, and P3) and Group (TD and ASD) on SD1 was greatest for visual (p = .001), followed by auditory (p = .006), and tactile (p = .006) stimuli; the interaction effect on the SD1/SD2 ratio was greatest for the visual task (p = .011), followed by the tactile task (p = .06); no significant interaction effect was observed for the auditory task (p = .106). For active sensory processing, the interaction effect between Condition (R0 and P4) and Group (TD and ASD) on SD1 was significant (p = .008); there was a marginally significant interaction effect on the SD1/SD2 ratio (p = .079). The regression-modeling analysis of this study found that the HRV measured in the sensory experiment was predictive of the occurrence of maladaptive response to sensory stimuli at home and at school.
This study has implications for research and clinical practice. The findings, in Phase 1, of the indifferent response patterns and inconsistency of responses to sensory stimuli across environments in children with ASD provides evidence of the occurrence of sensory processing difficulty in these children and suggests the importance of further investigation into the underlying mechanisms of sensory processing difficulty in children with and without ASD. The findings in Phase 2 provide evidence of suboptimal autonomic functioning in children with ASD at rest and upon administering sensory challenges. The results of this study provide further support for the usefulness of defining the sensory deficits of children with ASD as problems with self-regulating sensory processing. For clinical practice, the sensory checklist could be applied as a screening tool to detect children's sensory processing difficulties or to document the occurrence of maladaptive behavior. Because home and school environments are different, researchers should utilize different instruments to measure their behavioral data in either environment. Moreover, the validity of autonomic responses in sensory processing difficulties should be examined. Further verification of the structure of self-regulating sensory processing is suggested.
Rights: All rights reserved
Access: open access

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