Article Review

Imagine that you are faced with the following challenge. You must discover the internal structure of a system that contains tens of thousands of units, all generated from a small set of materials. These units, in turn, can be assembled into an infinite number of combinations. Although only a subset of those combinations is correct, the subset itself is for all practical purposes infinite. Somehow you must converge on the structure of this system to use it to communicate. And you are a very young child.

This system is human language. The units are words, the materials are the small set of sounds from which they are constructed, and the combinations are the sentences into which they can be assembled. Given the complexity of this system, it seems improbable that mere children could discover its underlying structure and use it to communicate. Yet most do so with eagerness and ease, all within the first few years of life.

Below we describe three recent lines of research that examine language learning, comprehension, and genesis by children. We begin by asking how infants break into the system, finding the words within the acoustic stream that serves as input to language learning. We then consider how children acquire the ability to rapidly combine linguistic elements to determine the relationships between these elements. Finally, we examine how children impose grammatical structure onto their perceived input, even to the extent of creating a new language when none is available. These investigations provide insight into the ways in which children extract, manipulate, and create the complex structures that exist within natural languages.

Next Section

Discovering the Units of Language

Before infants can begin to map words onto objects in the world, they must determine which sound sequences are words. To do so, infants must uncover at least some of the units that belong to their native language from a largely continuous stream of sounds in which words are seldom...