Relationship of proximal and distal function in motor development.

This study questions the validity of the principle of a proximo-distal direction of motor development and the idea that distal skill emerges out of and is dependent upon proximal control. To determine the relationship between proximal and distal motor function, 12 normal infants (9 girls, 3 boys), 30-weeks of age, were recorded on videotape while reaching for a one-inch red cube contained in a specially designed form board. Their visually guided reaching (proximal) ability and prehensile (distal) skills were rated on nonstandardized scales. No significant linear relationship was found between proximal and distal motor behavior. The conclusion that distal development does not necessarily follow proximal motor development is offered. The possibility that two different motor-control systems governin; proximal and distal function is considered. Reconsideration of the proximo-distal sequences currently used in treating motor-system dysfunction is recommended.