MLU and Brown’s 14 Morphemes
In this lab, you will learn how to identify and code morphemes within a sample.
You also will calculate a child’s
average utterance length (MLU) (you did some of this last week).
Average utterance length is commonly referred to
as mean length of utterances (MLU).
As we have discussed, one can calculate MLU at the word level or the
We will calculate MLU at the morpheme level to help us learn more about morphemes.
discussed in class and your textbook, MLU is a general index that is useful for describing a child’s general language
The textbook and lecture notes on Roger Brown’s work should also be useful for this lab.
It’s important to
remember that only
complete and intelligible
utterances of the child’s are used to calculate MLU.
If you were doing this as a speech language pathologist, you would use 100
utterances, although at times we calculate MLU on children who produce less.
The formula for calculating MLU in morphemes is:
number of morphemes / number of complete and intelligible utterances
The Analyze program of SALT calculates MLU for you using all complete and intelligible utterances.
All you need
to do is add “/” to words in samples that have bound morphemes.
You also need to put a * in front of morphemes
when the child omits a morpheme.
For example, if the child says “two egg” or “I have ball”, you would write “two
egg/*s” or “I have *a ball” to indicate that the child did not produced the morphemes that were expected in the adult
grammar. To do this analysis, you must learn how to code Brown’s 14 morphemes.
The 14 morphemes are:
articles a, an, the (a ball, an apple, the car)
preposition in (in the store)
preposition on (on the table)
present progressive (I am swimming)
regular past tense (I jumped)
irregular past tense (john fell)
third person regular (mary jumps)
third person irregular (she has it, she does it, she says it)
regular plural (I have two cats)
possessive (Mary’s hat)
contractible copula be (I am happy)
uncontractible copula be (am I happy?)
contractible auxiliary be (he is walking)
uncontractible auxiliary be (is chris walking?)
Students have the most trouble with
third person regular and irregular
so below is a bit
more information about these forms.
In English, the copula BE is when the BE form (is, are, was, were, am)
is used as a main verb as in the
utterances below. Notice that the BE form comes before nouns and adjectives.
I am happy, You are Mary, He is funny; We are the Tigers; They are the losers; I was happy; You were Married, He
was funny, We were the Tigers, They were the losers.