Morphology is the aspect of language concerned with the rules governing change in word
meaning. Morphological development is analyzed by computing a child’s Mean Length
of Utterance (MLU). Usually, a sample of 50 to 100 utterances is analyzed to draw
conclusions about the child’s overall production. Each word a child produces is broken
down into morphemes. A morpheme is the smallest, indivisible unit of meaning. For
example, the word “walk” is one morpheme, while “walked” is two morphemes: “Walk”
carries its own meaning and “ed” signifies past tense. Young children often combine
words to convey one meaning or idea. Consequently, words such as “gonna” count as
one morpheme. As adults, we understand that “gonna” really consists of both “going”
and “to”, each having meaning. After counting the morphemes for each of the child’s
utterances, they are totaled and divided by the total number of utterances. The formula is
MLU= Total number of morphemes
Total number of utterances
A child’s MLU typically corresponds closely to their age. Roger Brown described five stages of language development based on MLU.
The following table outlines typical MLU development:
Morphological acquisition is best outlined by Brown’s Fourteen Grammatical Morphemes.
The chart below details at what age each morpheme typically emerges.
|Morpheme||Example||Age of Mastery*|
|Present Progressive – ing||Mommy driving||19-28|
|In||Ball in cup||27-30|
|On||Doggie on sofa||27-33|
|Regular plural -s||Kitties eat my ice cream.|
Forms: /s/, /z/ and /iz/
Cats, Dogs, Classes, Wishes
|Irregular past||Came, fell, broke, sat, went||25-46|
|Possessive ‘s||Mommy’s balloon broke|
Forms: /s/, /s/ and /iz/ as in
(Verb to be as main verb)
(Response to “Who is sick?)
|Articles||I see a kitty.||28-46|
|Regular past –ed||Mommy pulled the wagon|
Forms: /d/, /t/, /Id/
Pulled, Walked, Glided
|Regular third person -s||Kathy hits|
Forms: /s/, /z/, and /iz/
|Irregular third person||Does, has||28-50|
|Uncontractible auxiliary||He is.|
(Response to “Who is
wearing your hat?”)
|Contractible copula||Man’s big|
Man is big
|Contractible auxiliary||Daddy’s eating|
Daddy is eating
Sentence forms begin to develop as early as 12 months of age. Sentences can take on several different forms, including declarative, negative, interrogative, embedded and conjoined.
The following table details the development of each:
|Early I |
|12-22||Agent + Action;|
all gone, gone
|Yes/no questions |
asked with rising
a single word;
what and where
|Serial naming |
Verb + Obj.
|No and Not used|
in and on
|No, not, don’t,|
and can’t used
|31-32||Subj. + aux.|
verb + objet.
verb forms can,
do have will and
verbs do, can and
to appear in
|But, so, or|
in subj. +
copula + X
|Won’t appears||Aux. Verbs|
do, can, and
will appear in
and subject in
appear with verbs
such as think,
guess and show;
embedded wh questions
subj. + aux.
verb + X
appear at the
ends of sentences
subj. + aux.
ind. obj. +
appear within the
above an MLU of
but and so
MLU of 5.0
By age five, a child is able to use most of the major variations of the English language.
The order that these varieties are acquired indicates a pattern of cognitive, social and
learning growth. Language continues to develop into early adulthood to include more
sophisticated usage. For more on language development, consult the following
Adrian , A. (Ed.). (1995). Lingistics: an introduction to language and communication.
4th ed. Cambridge, MA: MIT Press.
Owens, R. (2001). Language development: an introduction. 5th ed. Needham Heights,
MA: Allyn and Bacon.