Offline and online de novo motor skill learning differs in young children and adults.

Learning motor skills is fundamental to development. While adults typically outperform children on novel motor tasks, some evidence supports a developmental advantage in motor skill learning for young children. However, most research has focused on motor sequence learning tasks, thus little is known regarding age-related differences in other forms of skill learning, such as de novo motor learning. De novo paradigms involve learning a novel association between movement and its expected outcome and may be more relevant to real-world tasks. In this study, we examined de novo learning using a mirror reversal task in young children (ages 5-8) and adults (ages 18-25) over 3 separate sessions (initial practice, 24-hour retention, 7-day retention). Performance was measured by two metrics that reflect learning the task rule (initial direction error, IDE) and optimizing movement kinematics (path length, PL). Adults out-performed children across all testing and retention sessions but on average, all participants showed improvement in performance with practice. Adults had greater online learning for both IDE and PL. Offline learning was greatest in 8 year old children for IDE, with 5-year-olds and adults showing some performance decrements during retention tests. Consistent with prior studies, these results showed potential developmental advantages for offline but not online learning of de novo task rules and motor control required to optimize the task. We postulate these findings are linked to ongoing neuroplasticity of sensorimotor systems in young children.