system during visual tracking in children

23 Motor skills improve with age from childhood into adulthood and this improvement is reflected 24 in the performance of smooth pursuit eye movements. In contrast, the saccadic system 25 becomes mature earlier than the smooth pursuit system. Therefore, the present study 26 investigates whether the early mature saccadic system compensates for the lower pursuit 27 performance during childhood. To answer this question, horizontal eye movements were 28 recorded in 58 children (ages 5-16) and 16 adults (ages 23-36) in a task that required the 29 combination of smooth pursuit and saccadic eye movements. Smooth pursuit performance 30 improved with age. However, children had larger average position error during target tracking 31 compared to adults but they did not execute more saccades to compensate for their low 32 pursuit performance despite the early maturity of their saccadic system. This absence of 33 error correction suggests that children have a lower sensitivity to visual errors compared to 34 adults. This reduced sensitivity might stem from poor internal models and longer processing 35 time in young children. 36