The Development of Compositionality in Language and Thought

Compositionality is the property of a representational system whereby complex meanings arise from the combination of simpler meaningful elements. Here we take a developmental perspective to understand the origins of compositional representational systems and their relation to language—an issue that bears on longstanding debates in cognitive science about the structure of the human mind. Based on our review, we conclude that ( a ) well-controlled evidence for compositional abilities during language acquisition remains scarce, although some studies suggest infants begin to understand specific multiword combinations during the second year of life, and ( b ) the key computation underlying compositionality—function application—can be observed in infancy during the first year of life, well before, and even outside, compositional language. These findings suggest the mind may support compositional operations prior to the emergence of compositional language, while leaving open questions about how the development of compositional thought and compositional language interact.