Explicit representation of relations plays some role in virtually all higher cognitive processes, but relational knowledge has seldom been investigated systematically. This paper considers how relational knowledge is involved in some tasks that have been important to cognitive development, including transitivity, the balance scale, classification…

Reviews "Levels of Cognitive Development," which presents a theory of cognitive development integrating discrimination- learning research with understanding of higher cognitive processes. Argues that strengths include its presentation of systematic research and providing continuity between past and present models. Weaknesses include…