Children learn new words very quickly
The following chart illustrates the rate at which children learn new words:
Age Number of words used
18 months 50+ *
2 years 300
5 years Aprox 3000
7 years Aprox 4000
*Children can understand a lot more words than they can say. Although an 18 month old child can only actively produce 50 words, they can understand aproximately 250.
As a child gets older, their vocabulary increases and their grammar becomes more accurate and complex.
Nelson's early vocabulary study
Katherine Nelson conducted a study of an eighteenth month old's first fifty words. Nelson created five new categories for a child's early vocabulary:
1. Classifying objects (eg. dog, ball, cat)
3. Specific objects (eg. mummy, daddy)
4. Modifying words (eg. teeny, big)
5. Social words (eg. hello, bye, yes, no)
Over and underextension
Overextension = Where a child uses a word refer to different things which are related.
Underextension = Where a child makes restrictive use of a word.
Rescorla's analogical and categorial extensions
Analogical = Where a word is used to refer to several different things which bear physical/functional similarities.
Categorial = Where a word is used to refer to things in a similar category.