Patterns of object-name extension in production.

The evolution of young children's categories, as measured by category name production, was studied. The focus was on categories whose names initially were overextended. Four children (initially aged 1.1 to 1.3) were visited at home twice a week over a four- to six-month period, until they were approximately 1.7. The play sessions included elicitations of the names of specially chosen objects. Results indicated that, as predicted, four sequences of category evolution were found, formed by the intersection of two factors: overlap vs. mutual exclusivity and first re-assignment separate vs. first re-assignment joint. As expected, most sequences involved initial overlap, and the choice of first reassignment option varied as a function of the relationship (hierarchical or non-hierarchical) between the initial child-basic category and the new category.