Studies have found that children with Autism Spectrum Disorder (ASD) have a rigidity of motor plans and difficulties planning and executing movements (Eigsti et al., 2013). Children with ASD also exhibit repetitive behaviors such as nail biting and rocking back and forth. When planning for movements, repetitive behaviors might manifest as difficulty in formulating new or switching between different motor plans. In typically developing individuals, sequential actions often exhibit hysteresis, which is a phenomenon that explains that the way an individual chooses a specific motor plan could be influenced by recent, similar motor actions. We sought to determine if hysteresis was stronger in children with ASD and if this was influencing the planning and execution of a motor task. A rotation motor task was created to evaluate the rigidity of motor planning capabilities and hysteresis of five children with ASD (7-9 years old). A control group, consisting of 5 age-matched participants was also tested. The participant sat across from the researcher. A stick was placed in different orientations around a circle grid system containing 24 positions. The researcher would move the stick counterclockwise or clockwise in these positions, reveal the position to the participant, and ask them to return it to the home position. Researchers measured the position at which the child switched from a thumb up to a thumb down grasp in both the clockwise and counterclockwise direction. While moving the stick clockwise, the peak switch (the switch where children adopted a comfortable grasp) occurred much later for children with ASD. These children also switched their grasp positions less frequently than the control group. The results of this study suggest that changing a grasp was more costly than being comfortable while performing the action, and that hysteresis was more prevalent in children with ASD than in the control group.
Available at: http://works.bepress.com/breanna-studenka/2/