Comparison of the effects of task complexity in children with autism spectrum disorder and typically developing children

Özkan, Ş. (2026). Comparison of the Effects of Task Complexity in Children with Autism Spectrum Disorder and Typically Developing Children. Master's Thesis, Istanbul Atlas University, Graduate Education Institute, Department of Occupational Therapy, Istanbul. Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition that, in addition to social communication and behavioral characteristics, exhibits marked differences in motor performance, gait, and postural control mechanisms compared with typically developing (TD) children. Because daily activities involve simultaneous cognitive and motor demands, evaluating motor performance and postural control under dual-task conditions has become increasingly important. The aim of this study was to compare the effects of single-task and dual-task conditions on motor performance and postural control in children with ASD and TD children, and to examine how cognitive load influences physical task performance in both groups. A total of 90 children aged 6–16 years participated in the study, including children with ASD (n = 45) and TD children (n = 45). At baseline, demographic characteristics as well as scores from the Childhood Autism Rating Scale (CARS) and the Pediatric Balance Scale (PBS) were recorded. Motor performance of all participants was assessed during sit-to-stand and walking tasks under single-task and dual-task conditions using smartphone-based applications, while postural control was evaluated using a Nintendo Wii Balance Board. During the dual-task condition, participants were required to perform the motor tasks while simultaneously completing a cognitive task involving verbal working memory. Dual-task cost was calculated to quantitatively determine performance differences between single-task and dual-task conditions. The results showed that, in the ASD group, dual-task conditions did not lead to a significant difference in sit-to-stand test outcomes compared with the single-task condition (p > 0.05). However, under dual-task conditions, the ASD group demonstrated significant changes in walking time (p < 0.001), step count (p = 0.001), step time (p < 0.001), step time symmetry (p = 0.005), step length symmetry (p = 0.014), walking speed (p = 0.003), and cadence (p = 0.003). In the TD group, although changes were observed in similar parameters, step time symmetry (p = 0.897), step length (p = 0.327), cadence (p = 0.079), and vertical center-of-mass displacement (p = 0.470) did not reach statistical significance. In between-group comparisons, only step time symmetry showed a significantly greater change in the ASD group compared with the TD group (p = 0.048, d = 0.78). The dual-task score in the sit-to-stand test was significantly higher in the TD group than in the ASD group (p < 0.001, d = 2.03). Regarding postural control, the ASD group showed significant changes under dual-task conditions in medio-lateral (ML) variance (p < 0.001), antero-posterior (AP) mean (p = 0.047), mean force (p = 0.045), and force variance (p = 0.004). In contrast, no significant differences between single-task and dual-task conditions were observed in balance measures in the TD group (p > 0.05). However, a significant between-group difference was found in the center-of-pressure ML variance cost (%) parameter, with the ASD group showing greater changes than the TD group (p = 0.029). These findings indicate that dual-task conditions negatively affect performance in sit-to-stand, gait, and Nintendo Wii balance measures in children with ASD, resulting in significant changes and higher dual-task costs compared with TD children (p < 0.001, d = 2.03–2.35). This highlights that impairments in gait symmetry and postural control under cognitive load make it more difficult for individuals with ASD to maintain motor performance, emphasizing the need to address motor and cognitive components together in rehabilitation programs. Keywords: Autism Spectrum Disorder, Walking, Postural Balance, Child