Mapping the Terrain of Language Learning

This article explores how linguistic typology-the study of the variation found in human languages-can contribute to the study of language learning. All features that differentiate human languages must be acquired by their speakers, which suggests a concrete lower bound on what is learned. I discuss how the notion of the parameter explains observed implicational universals. I review some established parameters, and then I explore the idea that these parameters are logically ordered in a way that well-designed language learners can exploit to structure the learning process efficiently. Finally, I survey the literature on the acquisition of parameter settings by children, which suggests that children learn these settings in exactly the order predicted. Linguistic typology thus provides a precise linguistic map of the language-learning process.