W-Sitting and Sociomotor Behaviors in Toddlers with Autism Spectrum Disorders: True or False?
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interactions and communication, restricted interests, and stereotyped or repetitive behaviors. While abnormal motor features are not considered as diagnostic criteria, they are observed in more than 85% of individuals with ASD and are the earliest reliable predictor of a later ASD diagnosis among high-risk siblings of children with ASD. Movement variability is critical for social development and environmental exploration, affecting both autonomy and language development. The purposes of this study were to investigate the overall frequency and variety of gross motor behaviors in typically developing children (TD) and age-matched children with ASD during play with a parent and to focus on two distinctive motor behaviors: a) W-sitting position commonly reported as problematic and b) sociomotor dyadic Forced Transitions.
Using our pre-established reliable videocoding we tested three hypotheses: (1) compared to TD children, children with ASD will have reduced frequency and variability of posture changes due to motor constraints and restricted social behaviors; (2) more children with ASD exhibit W-sitting based on reported clinical observations; and (3) more parents of ASD children will initiate Forced Transitions to facilitate reciprocity and responsiveness during play.
Participants (TD=20; mean age=39.5 months; ASD=20; mean age=34.8) were videotaped during home-based play sessions with a parent as part of a longitudinal study to examine language development in children with ASD. Physical therapy students trained in videocoding and blind to ASD diagnoses independently rated the first five minutes of a 30-minute interaction using Datavyu software. Postures were categorized into “static” (sitting, standing, kneeling) and “dynamic” (locomotion involving moving from one location to another). Each posture (standing, sitting) was expanded into more specific positions (half-kneel, W-sitting). Codes for W-sitting (sitting posture where the bottom is on the ground and legs are splayed to opposite sides of the body; legs make a “W”) and Forced Transition (child is physically moved by the parent) were developed, and inter-rater reliability for all codes ranged from 0.91 to 1.0 at a 95% confidence level. Data were analyzed in MATLAB R2017b, and descriptive statistics were calculated as Mean (SD), and Frequencies [%(n)].
Compared to age-matched TD children, children with ASD exhibited a similar frequency and variability of posture changes. As expected, Forced Transitions were significantly more frequent among the ASD dyads. However, no significant differences were found between the groups for W-sitting. In each group, 7 children exhibited W-sitting.
The study emphasizes the benefit of developing interdisciplinary assessment between psychologists and physical therapists using standardized motor coding to evaluate best practices for children’s motor autonomy and social exploration. Contrary to common beliefs about links between W-sitting and developmental delays, our results showed equal frequencies of W-sitting between groups. A survey of pediatric therapists revealed that W-sitting in children 12 to 96 months is common and often treated despite a lack of clear scientific evidence and access to longitudinal data. Our future longitudinal coding will inform on motor and related language trajectories.