A total of 192 second- to sixth-grade children, showing three different levels of class-inclusion answers (failure, correct answer based on counting, correct answer based on logical reasons), performed four necessity tasks. Results are discussed with reference to individual and constructive generalization processes. (Author/RH)

Derives two models for conceptualizing figure similarities from Piaget's developmental theory of spatial reference systems. An experiment on a two alternative forced-choice similarity matching task revealed age differences in observer dependence among children and young adults. Concludes that some Euclidian space concepts are achieved as formal…

Reports results of two experiments to test recognition decisions of increasing difficulty among preschool children. Increasing levels of difficulty were perceptual identity, common object-class, and either taxonomic category or complementary pair formation. (Author/DB)