Two experiments used a formal model of developmental discontinuity derived from catastrophe theory to test whether the transition from Rule I to Rule II on the balance scale task proceeds discontinuously from ages 6 to 10, focusing on five catastrophe flags. Found that bimodality, inaccessible region, hysteresis, and sudden jump were clearly…

Part of a prospective longitudinal study examining factors that account for developmental outcomes for high-risk children, this investigation focused on how successful adaptation at 12 and 18 months is related to adaptation at 24 months, 42 months, and 4.5 to 5 years of age. Assessments at each age were designed to indicate how the child was…