First, explain generally the pattern of lexical development. Second, explain why children are able to so rapidly learn vocabulary and why it seems to be more difficult for adults.

What will be an ideal response?

Ans: Students should discuss lexical development as the growth of vocabulary as children acquire a language. It appears children’s first 50 words are gained more slowly across the 12- to 18-month time period with a focus on general nouns, then around 18 months they demonstrate naming insight and reach almost 10,000 words by the age of 6 years. Some researchers have shown children learn an average of 13 new words per day up through age 18. Children seem able to do so because of fast mapping to initially learn meanings then extended mapping, where they are able to consider multiple dimensions of meaning, which requires more extended exposure to the vocabulary. They use a series of constraints to learn: 1) whole object assumption to see a new object and assume the new word applies to the entire object, 2) mutual exclusivity principle where children assume objects have one, and only one, label (if given a new label, they apply it to the new object), 3) taxonomic principle is used to generalize a new word to other, similar objects.