Lateral asymmetries in the development of the overarm throw

Lateral asymmetries of manual, pedal, and ocular preferences, and motor asymmetry in the performance of the forceful overarm throw were analyzed in 71 children aged 4 to 10 years old. Performance with each side of the body was assessed on the basis of qualitative analysis, as proposed by M. A. Roberton and L. Halverson (1984) for identification of developmental stages by components of the task. Lateral preference was indicated by the frequency the children used the right or the left side of their body to carry out different manual, pedal, and ocular tasks. The overarm throw movement pattern was developed with both sides of the body but at different levels. Development of the nondominant side lagged behind that of the dominant side at all ages; a significant asymmetry in performance detected in the 4-year-olds was stable up to the age of 10 years. Indices of asymmetry for lateral preference and performance were found to be specific because no consistent correlations were observed among them throughout the age periods studied. Those results show the multidimensional character of human laterality and imply a property of motor development that prevents asymmetry of performance from increasing because of unilateral practice.