Reaching to throw compared to reaching to place: a comparison across individuals with and without Developmental...

When picking up an object, adults show a longer deceleration phase when the onward action has a greater precision requirement. Tailoring action in this way is thought to need forward modelling in order to predict the consequences of movement. Some evidence suggests that young children also tailor reaching in this way; however, how this skill develops in children with Developmental Coordination Disorder (DCD) is unknown. The current study compared the kinematics of reaching to an object when the onward intention was: to place the object on a target (either with high or low precision requirements), to throw the object or to lift the object vertically. Movements of both adults (N = 18) and children (N = 24) with DCD and their age-matched controls were recorded. The typically developing adults discriminated across all action types, the adults with DCD and the typically developing children only across the actions to place and throw and the children with DCD only between the actions to lift and throw. The results demonstrate developmental progression towards fine tuning the planning of reaching in relation to onward intentions. Both adults and children with DCD are able to plan movement using inverse models but this skill is not yet fully developed in early adulthood.