Abstract
Even infants can recognize physically impossible patterns of motion, seem to expect correct trajectories, and as they develop motor skills, move as necessary to achieve a goal. Yet in adulthood, the majority of people perform poorly when asked to make explicit predictions about motion in the same problems, and are influenced by irrelevant surface features. To characterize the changes that occur during development and the nature of individual differences, we developed a new assessment of force and motion that is age appropriate for both 6-year-old children and adults. Participants at both ages were generally able to reason at above-chance levels about motion in one dimension, although adults showed superior performance. On problems involving motion in two dimensions, adult males did better than boys, but adult females were equivalent to girls. These data provide the basis for a reinvigorated investigation of the factors supporting the development of the ability to think about force and motion.