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The Relationship Between Autism Symptoms and Arousal Level in Toddlers with ASD, As Measured By Electrodermal Activity
Electrodermal activity (EDA) is a measure of skin conductance and is often used to determine the level of emotional arousal in children and adults (Dawson, 2000). Previous studies have examined EDA in the context of face recognition, gaze direction and eye contact in children and adults with Autism Spectrum Disorders (ASD) using EEG and eye-tracking protocols (Joseph, Ehrman, McNally, & Keehn, 2008; Kylliainen & Hietanen, 2006; Kylliainen et al., 2011). However, little is known about EDA in toddlers with ASD and even less is known about it during real-world behavioral assessments.
Objectives:
To use EDA measurements to examine differences in reactivity between toddlers with ASD and their typically developing (TD) peers during a behavioral assessment of social communication.
Methods:
21 toddlers (10 TD, 11 ASD; mean age=22 months) received the Communication and Symbolic Behavior Scale (CSBS) as part of a comprehensive assessment of social functioning, communication skills, and development. The CSBS comprises a number of activities designed to elicit social and communicative behaviors in toddlers. These include interaction with animal figurines, toy cars, books, wind-up toys, bubbles, balloons, and a snack session. The activities were grouped into four categories: books, animals, mechanical toys, and temptation episodes. During the 30 minute session, participants wore a sensor on their ankle (Affectiva Q-Sensor) that measured EDA in microsiemens at 8 Hz. The first second of each activity was used as a baseline measure. We used the largest absolute change to identify the magnitude of change from baseline during each activity.
Results:
We used a 2 (diagnosis) by 4 (activity) mixed factorial design and ran a linear mixed models ANOVA. Because the children were likely to vary in verbal abilities based on diagnostic group, we controlled for Verbal DQ scores as measured on the Mullen Scales of Early Learning. In TD toddlers, there was a significant difference in the absolute change in EDA between the animal toys and the temptation tasks (p<0.05). However, this was not the case in children with ASD. For these children, there was a significant difference in EDA between the animal toys and the mechanical category which includes cars, helicopters, spinning and wind-up toys (p<0.01).
Conclusions:
Children with ASD have a dissimilar reaction to activities on the CSBS as compared to their typically developing peers. Both groups responded similarly to the animal toys, which are generally the least exciting and interactive items. However, while TD children showed a greater change in EDA during the “temptation” toys which require them to interact with the examiner in order to operate the object, those with ASD showed a heightened response to mechanical toys. These results are consistent with previous findings demonstrating that children with ASD are more likely than TD children to have a circumscribed interest in mechanical systems (Turner-Brown, Lam, Holtzclaw, Dichter, & Bodfish, 2011). These preliminary results offer physiological evidence of arousal differences between toddlers with ASD and their typical peers upon presentation of specific stimuli.