Theories of Language Development

Language development is a critical area in cognitive psychology that explores how humans acquire, use, and understand language. Research has shown that children progress through various stages in language learning. These stages have been categorized into distinct developmental milestones. One of these crucial milestones involves the ability to form complex sentences, which generally occurs after the initial phase of acquiring vocabulary and basic grammar rules.

Which of the following theories best explains how children reach the advanced stage of language development, where they begin to demonstrate an understanding of grammar and syntax beyond simple word combinations?