The first stage of combinatorial speech is better described as variable than uniform. Talk of variants obscures two different aspects of language (knowledge and use) and two different aspects of language development -- acquisition of the grammar (competence) and deployment of the grammar in speaking and listening (performance). Null subjects and…

Research in language development has only recently begun to focus on the inherent variability of language. Previous studies have explored at what age children begin to produce variable linguistic forms and how these forms progress through development. While children produce adult-like variation early on, some variable forms take longer to acquire…

For adults, "no" and "not" change the truth-value of sentences they compose with. To investigate children's emerging understanding of these words, an experimenter hid a ball in a bucket or a truck, then gave an affirmative or negative clue (Experiment 1: "It's not in the bucket"; Experiment 2: "Is it in the…

Across a diverse range of languages, children proceed through similar stages in their production of causal language: their initial verbs lack internal causal structure, followed by a period during which they produce causative overgeneralizations, indicating knowledge of a productive causative rule. We asked in this study whether a child not…