Children's Production of Unfamiliar Word Sequences Is Predicted by Positional Variability and Latent Classes in a Large Sample of Child-Directed Speech.

We explore whether children's willingness to produce unfamiliar sequences of words reflects their experience with similar lexical patterns. We asked children to repeat unfamiliar sequences that were identical to familiar phrases (e.g., A piece of toast) but for one word (e.g., a novel instantiation of A piece of X, like A piece of brick). We explore two predictions-motivated by findings in the statistical learning literature-that children are likely to have detected an opportunity to substitute alternative words into the final position of a four-word sequence if (a) it is difficult to predict the fourth word given the first three words and (b) the words observed in the final position are distributionally similar. Twenty-eight 2-year-olds and thirty-one 3-year-olds were significantly more likely to correctly repeat unfamiliar variants of patterns for which these properties held. The results illustrate how children's developing language is shaped by linguistic experience.