Dissociating encoding and post-encoding stages in cognitive-motor coordination across late childhood and young...

Cognitive-Motor coordination (CMC), the ability to coordinate cognitive and motor tasks simultaneously is essential for daily functioning and children's development. While extensive research shows that motor tasks can modulate cognitive performance, the reverse influence-how cognitive tasks modulate motor performance-remains debated, particularly regarding the mechanisms and age-related differences across cognitive processing stages. To address this gap, the present study employed a stage-based CMC task in three age groups: 7-8-year-olds, 9-12-year-olds, and young adults. Participants simultaneously performed a cognitive task (subitizing for small numerosities and estimation for larger ones) while maintaining different levels of grip force (low-, medium-, and high-level motor loads). Motor load modulated the error rate of estimation in a U-shape pattern-with optimal cognitive performance occurring under medium motor loads-and this pattern was evident in both children and young adults. Critically, the stage-based design enabled us to assess motor performance during encoding and post-encoding stages. CMC differed across stages under medium and high motor loads. Specifically, during the encoding stage, grip maintenance was better during estimation than subitizing, and this estimation advantage was observed only in children. In contrast, during the post-encoding stage, grip maintenance was better during subitizing than estimation, and this subitizing advantage was observed across all age groups. These findings demonstrate that cognitive processing affects motor control differently across cognitive processing stages, with each stage exhibiting distinct age-related changes. The "cognitive stage-dependent" modulation mechanism provides new insights into the nature and development of CMC.