Summary. Performance on Inhelder and Piaget's pendulum problem was obtained as a validating measure in a study of the transition from concrete to formal thinking. The sample consisted of 236 children aged from 10 to 14 years. A detailed scoring procedure was devised, which distinguished method from content aspects of performance on the problem and which allows categorisation of each child into one of nine developmental stages. Quantitative performance scores were also derived.
Overall level of performance on the pendulum problem is strongly related to age, but not to sex or to school attended. In general, the results support Inhelder and Piaget's account of the transition from concrete to formal thinking. However, a specific problem, for their theory, arises from the relationship between method and content aspects of performance in the early formal operational stage (IIIA). This problem is discussed in detail and attention is drawn to the effects of a child's expectations on his performance.