Developing Morphology

By 2-2½ years: use of some inflectional morphemes to indicate the grammatical function of nouns and verbs.

The first to appear is the -ing form in expressions such as cat sitting and mommy reading book.

Overgeneralization khái quát hóa quá mức: in L1 acquisition, using an inflectional morpheme on more words than is usual in the language

• The child overgeneralizes the rule of adding -s to form plurals and will talk about foots and mans. 

• When the alternative pronunciation of the plural morpheme used in houses (i.e. ending in [-əz]) comes into use, overgeneralization happens again and forms such as boyses or footses can be heard. 

• At the same time as this overgeneralization is taking place, some children also begin using irregular plurals such as men appropriately for a while, but then overgeneralize again and producing expressions like some mens and two feets, or even two feetses.