What is indicated by a vocabulary explosion around 18 months?

A vocabulary explosion around 18 months signifies a remarkable period in language development when children rapidly acquire a large number of words. During this phase, it is common for toddlers to transition from using single words to incorporating a broader range of vocabulary into their speech. This surge can be attributed to various factors, including increased cognitive abilities and social interactions.

As children begin to make connections between objects, actions, and their corresponding words more effectively, they can learn and use new words at an astonishing pace. This phenomenon is often observed in the context of natural social settings where children are encouraged to communicate, and exposure to language is heightened. A vocabulary explosion can profoundly influence their overall language skills, setting the stage for further linguistic development, such as combining words into phrases and sentences.

The other options do not accurately represent this stage of language development—children are not limited to learning one word at a time, they are not necessarily producing more complex sentences at this early stage, and they continue to imitate sounds as part of their language acquisition process. All these aspects support the understanding of a vocabulary explosion as a time of significant verbal growth and word acquisition.