Words Are Not Merely Features: Only Consistently Applied Nouns Guide 4-year-olds' Inferences About Object Categories

Abstract

Although there is considerable evidence that nouns highlight category-based commonalities, including both those that are perceptually available and those that reflect underlying conceptual similarity, some have claimed that words function merely as features of objects. Here, we directly test these alternative accounts. Four-year-olds (n = 140) were introduced to two different novel animals that were highlighted with nouns, adjectives, or stickers. Children heard a nonobvious novel property applied to the first animal and were asked whether this property applied to other animals that filled the similarity space between the original two animals. When the two animals were named with the same noun, children extended the property broadly throughout the similarity space. When the animals were marked with adjectives or stickers, children adopted a similarity-based pattern. These findings demonstrate clearly that nouns exert a unique effect on categorization—they promote category formation and engage conceptual reasoning beyond perceptual similarity alone.

Acknowledgments

This research was supported by grants from the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, and the Canada Research Chairs program awarded to the first author, funding from the National Science Foundation (BCS-0843252) awarded to the second author, and funding from the NICHD (NICHD-HD-30410) awarded to the third author. We are grateful for the participation of all the children and parents. We also thank Hayli Stock, Natasha Nickel, Kimberley Freed, and Melanie Khu for their assistance with this research.

Notes

¹Analyses comparing children's generalizations to the Low Similarity objects to chance-levels indicate that only generalizations in the Consistent Noun condition were above chance-levels (p < .0001).