Basic-level individuals.

In this experiment, 4-year-old children interpreted a novel count noun taught ostensively for an unfamiliar object as referring to a basic-level kind (such as PERSON or DOG) rather than to a kind that individuates its members by type of situation (such as PASSENGER or PUPPY). Because ostension does not distinguish a basic-level kind from a situation-restricted kind, this finding suggests that children assume, as a default, reference to a basic-level kind rather than to a situation-restricted kind when they hear a count noun applied to an unfamiliar object in an ostensive definition. The experiment shows that the assumption guides children's interpretation only if the object is unfamiliar, and if no specific information is available calling for a situation-restricted kind interpretation. The proposed word-learning assumption is critical to an understanding of the psychologically privileged manner of individuation, and therefore, of quantification (e.g., counting) involving objects.