Esther Thelen

Esther Thelen (1941 to 2004) was a developmental psychologist whose research centred on how infants learn to move, reach and walk. She applied dynamical systems ideas, including chaos theory, to early motor development and argued that behaviour emerges as a pattern from many interacting influences in the body, the brain and the environment, rather than unfolding from a fixed internal programme. Her work on the A-not-B error and on the stepping reflex and spontaneous kicking of newborns became a touchstone for embodied accounts of cognition. She served as president of the Society for Research in Child Development and of the International Society for Infant Studies, and was a fellow of the American Association for the Advancement of Science.