Domain-general categorization in 14- to 24-month-old infants

The current experiments were concerned with the development of object categorization skills during the second year of life. Experiment 1 examined whether 18- and 24-month-old infants were capable of performing categorization at the domain-general level (i.e., very broad categories of animate and inanimate objects) using a sequential touching procedure. The 18-month-old infants categorized the objects at an above-chance level, but the 24-month-olds did not. However, the 24-month-olds demonstrated a higher percentage of cross-category touching (i.e., putting people on vehicles and furniture), which would make it difficult to demonstrate categorization using this particular procedure. In Experiment 2, 14-, 18-, and 24-month-old infants participated in a sequential touching task in which the part features of animate and inanimate objects were modified, allowing for a comparison of leg/wheel categorization (i.e., perceptually-based) and animate/inanimate categorization (i.e., conceptually based). None of the age groups performed either leg/wheel or animate/inanimate categorization at a level significantly greater than chance. Taken together, these results demonstrate that infants are capable of categorizing at a broad level during the middle of the second year of life, and that they do not use perceptual features as the sole basis for this categorization.