Class and conditional reasoning in children and adolescents

The development of the ability to comprehend and reason with class and conditional logic statements was examined in the light of Piaget's claim that prior to the age of 11-12 years children are limited to reasoning in terms of classes and relations but from the age of 11-12 years reasoning in terms of propositions becomes possible. Subjects from 5 years to 17.5 years were presented with several different comprehension and inference tasks with class and conditional logic statements. Evidence of differences in the ability of subjects under 12 years to verify class and conditional logic statements was consistent with Piaget's claim that the logical classification operations of the concrete subject enable him to interpret class inclusion statements but that the conditional interpretation of empirical information requires formal operational thinking. No distinction in performance between class and conditional statements was found on tasks which required an understanding of the logical consequences of the inclusion relation with subjects younger than first year secondary performing poorly on both class and conditional versions of an evaluation task and a syllogistic reasoning task. Significant changes in patterns of response at adolescence on the conditional verification task, the evaluation task and the syllogistic reasoning task supported Piaget's contention that there are qualitative changes in reasoning at adolescence although, as in other studies, errors in reasoning by adolescents indicated that Piaget overestimated the logical abilities of the formal subject and suggested that Piaget's logical model of cognition should be regarded as a model of logical competence