The Waxing and Waning of Movement: Implications for Psychological Development

Age-related changes in movement may have unappreciated implications for various psychological domains. To identify when it might play a key role in such domains, we describe a developmental trajectory for movement from infancy to adulthood. Participants in 12 studies (total N = 840) ranged in age from 6 weeks to 52 years, and all wore instrumented motion recorders that measured limb movement throughout 1 or 2 full days. We found an inverted U-shaped pattern in limb movements per hour that peaked in middle childhood, later than expected. This developmental pattern in motor activity has theoretical relevance for various aspects of physical, cognitive, social, and emotional development and implications for ADHD, educational practice, sex differences, functional immaturity, and the regulation of arousal.