Developmental improvements in reaching correction efficiency are associated with an increased ability to represent action mentally

• Motor imagery and online control follow parallel developmental paths in childhood.
• Developmental improvements in motor imagery predict faster online control of reaching.
• Action representations appear critical to the development of important motor skills.

We investigated the purported association between developmental changes in the efficiency of online reaching corrections and improved action representation. Younger children (6–7 years), older children (8–12 years), adolescents (13–17 years), and young adults (18–24 years) completed a double-step reaching paradigm and a motor imagery task. Results showed similar nonlinear performance improvements across both tasks, typified by substantial changes in efficiency after 6 or 7 years followed by incremental improvements. Regression showed that imagery ability significantly predicted reaching efficiency and that this association stayed constant across age. Findings provide the first empirical evidence that more efficient online control through development is predicted, partly, by improved action representation.