Individual and developmental differences in preschoolers' categorization biases and vocabulary across tasks.

This study bridges prior research on young children's use of taxonomic versus thematic relations to categorize objects with prior research on their use of shared shape versus shared function to categorize artifacts. Specifically, this research examined associations in children's categorization tendencies across these two dichotomies, including assessments of individual differences, developmental trends, and vocabulary level. Preschoolers (3- to 5-year-olds) completed a receptive vocabulary assessment and two match-to-sample tasks: one pitting (superordinate) taxonomic and thematic relations against each other and one pitting shape and function similarity against each other. The results revealed individual and developmental variation in children's cross-task categorization biases, with a predominant tendency to focus on both thematic and function relations that became increasingly stronger with age. In 3- and 5-year-olds, function-based categorization was also positively associated with verb vocabulary. These findings demonstrate an emerging tendency to focus on relational information during the preschool years that, among other learning effects, may benefit verb acquisition. The results are discussed in terms of the real-time processing and developmental factors that might contribute to the development of strategies for learning about objects and categories during early childhood.