In executing purposeful actions, adults select sufficient and necessary limbs. But infants often move goal-irrelevant limbs, suggesting a developmental process of motor specialization. Two experiments with 9- and 12-month-olds revealed gradual decreases in extraneous movements in non-acting limbs during unimanual actions. In Experiment 1, 9-month-olds produced more extraneous movements in the non-acting hand/arm and feet/legs than 12-month-olds. In Experiment 2, analysis of the spatiotemporal dynamics of infants' movements revealed developmental declines in the spatiotemporal coupling of movements between acting and non-acting arms. We also showed that the degree of specialization in infants' unimanual actions is associated with individual differences in motor experience and visual attention, indicating the experience-dependent and broad functional nature of these developmental changes. Our study provides important new insights into motor development: as in cognitive domains, motor behaviours are initially broadly tuned to their goal, becoming progressively specialized during the first year of life.
Bibliographical noteD'Souza, H. , Cowie, D. , Karmiloff‐Smith, A. and Bremner, A. J. (2017), Specialization of the motor system in infancy: from broad tuning to selectively specialized purposeful actions. Dev Sci, 20: e12409. doi:10.1111/desc.12409
© 2016 John Wiley & Sons Ltd.
- Child Development/physiology
- Motor Activity/physiology
- Psychomotor Performance