PROOF CONSTRUCTION - ADOLESCENT DEVELOPMENT FROM INDUCTIVE TO DEDUCTIVE PROBLEM-SOLVING STRATEGIES

Inductive and deductive approaches to the construction of problem-solv ing proofs were examined using a task that requires the discovery of a geometrical figure hidden behind a series of covers. It was proposed that during adolescence, with the acquisition of a formal reasoning co mpetence (as measured by Overton's [1990] version of Wason's selection task), there would be a transition from inductive to deductive proof construction strategies. One hundred adolescents were assessed on both the problem-solving proof task and the reasoning competence selection task. The results demonstrate that a formal level of reasoning compet ence is associated with taking a deductive approach to proof construct ion. Formal reasoners tend to construct a proof based on the use of a falsification strategy as demonstrated by their search for disconfirmi ng instances. A nonformal level of competence on the other hand is ass ociated with inductive approaches. In this situation nonformal subject s tend to employ a verification strategy as demonstrated by the genera tion of redundant information. Results support the hypothesis that the re is a cognitive developmental progression from an inductive approach to the construction of proofs to a deductive approach. (C) 1995 Acade mic Press, Inc.