Abstract
Through development children become increasingly expert in their ability to modify their motor responses according to changing visual information. An important aspect of this may be the ability to apply learnt rules to modify goal-directed actions operating under direct visual control. We studied development of this ability in four groups of children (n=10 for each group) aged between 5 and 12 years. Electromagnetic tracking equipment was used to document the kinematic features of aiming movement throughout its course from commencement to interception. The experiment consisted of 20 baseline trials and 60 further trials. For the baseline trials recorded before and after the experimental block, the child was required to move 25cm from a starting location to a stationary target 2cm in diameter (that the child knew would remain constant). A red target turning green was the signal to move. The experimental block consisted of four randomised conditions. Condition 1 consisted of 10 constant trials identical to baseline. Condition 2 consisted of 20 trials where the target ‘jumped’ either 10cm to the left or 10cm to the right, 10ms after movement commencement, Condition 3 consisted of 10 trials where the target turned red after the movement started, signalling the requirement to stop moving. In the fourth condition of 20 trials a blue distractor target appeared either 10cm to the left or right of the central target that remained as the central target. This paradigm revealed the developmental course of countermanding ability, online visual feedback correction capability and the aptitude to ignore distracting stimuli. The baseline trials allowed us to explore developmental patterns in strategy adoption when uncertainty is introduced within a movement task. The data shed light on the development of skilled visuomotor behaviour and constitute one of the most comprehensive descriptions of skilled movement development within this age group.