Children and Adults as Language Learners: Rules, Variation, and Maturational Change.

Here we overview our recent research investigating children and adults' learning of rules and variation. In all these studies, our findings are that children and adults differ in how they acquire linguistic patterns that are productive, variable, inconsistently used, or lexically restricted. Some of our studies examine children's learning of natural languages; other studies expose learners to miniature languages and then ask them to produce novel sentences or judge their grammaticality. In every case there are important differences between learners as a function of their ages. Young children learn categorical rules and categorically follow patterns that are widespread in natural languages, even when their linguistic input exemplifies these patterns only probabilistically. In contrast, adult learners reproduce the probabilistic patterns of the input. Older children are in between, producing regular patterns somewhat more often than they appear in the input but also acquiring some probabilistic variation. These results suggest that the outcome of learning is quite different at different ages and that many of the properties of natural languages may be shaped by the behavior of children as they learn their native languages.