When is a triangle not a triangle? Young children's developing concepts ofgeometric shape

This paper examines young children's developing concepts of geometric shape s. In Study 1, 54 children from preschool, second and fourth grades, and 12 adults completed a sorting task. Results suggested that older children rel y more on rule-based definitions and less on perceptual similarity than you nger children when making sorting judgments. The former transition occurs e arlier and apparently more abruptly than the latter. These results are gene rally consistent with Keil's (1989) description of a characteristic-to-defi ning shift. Study 2 examined the performance of 29 three- and 4-year-olds. Results suggested that few of these children relied on defining features wh en the overall domain of geometric shapes was considered. In both studies c hildren demonstrated a developmental shift at different times for different shapes. The complexity of each type of shape is proposed to explain these rates of development.