CDO 130-Fall 2009
SLS Morpheme Count Instructions
You will be examining the language growth of a child based on their use of morphemes. Remember that a
morpheme is the smallest unit of meaning in a language. There are 2 types of morphemes – both free and
bound. Free morphemes can stand alone and have meaning whereas bound morphemes have no meaning
on their own. They must be attached to a free morpheme to make sense.
Roger Brown was the individual who provided us with the ability to measure how children acquire speech
and language. His research, more commonly known as “Brown’s Stages” describes the syntactical or
structural development that children go through when acquiring speech and language. Brown traced the
development of syntax through 5 major stages. He was able to track this development by measuring the
mean length of utterance (MLU) in any given language sample of a child.
So what is MLU? When we have a sample of a child’s language, there may be some utterances that have
only single free morphemes (i.e. if a child says “No”) or some utterances that may contain four or five
morphemes (i.e. “I want to go outside”). Some utterances may contain only free morphemes while others
may have both free and bound morphemes. To calculate the mean (or average) length of a child’s utterance
we count the morphemes in each utterance, add the total, and divide by the total number of utterances.
EXAMPLE: Out of 50 utterances a child’s total morpheme count is 200
To figure out MLU take 200 and divide by 50
Total MLU = 4.0
What does all this mean? Well, one would expect that as a child gets older and learns more and more about
language, then their MLU or mean length of each sentence they speak would also get longer to reflect their
language growth. This is in fact what Roger Brown discovered. His research summarizes the five stages
children go through as they develop language, with each stage showing in increase in both age and MLU.
One goal for you to accomplish with this project is to determine what the child’s MLU is and what Brown’s
Stage corresponds to their sample. Remember that the Brown’s Stage that is assigned to each child is based
on MLU only and not their age!
RULES FOR COUNTING MORPHEMES AND COMPUTING MLU
1) Count the number of morphemes and total them for 50 utterances spoken by the child. Put the
number for each utterance in the column provided on your transcription.
2) Divide this total by the number of utterances (50) to get MLU.
3) Count both free and bound morphemes. Frequent bound morphemes include but are not limited
to:
a. Plural –s
b. Possessive –‘s
c. Past tense –ed
d. 3rd person present tense –s
e. Progressive –ing
4) Contractions such as “don’t” and “can’t” counts as 2 morphemes.
5) Count only the morphemes that are outside parentheses. DO NOT count as morphemes such
“fillers” as ‘um’ ‘uh’. Omit false starts and repetitions, which have been enclosed in parentheses,
from the morpheme count.
