The Development of Morphology & Syntax

Syntax

Allowable patterns (rules) for combining words into sentences.

Morphology

The study of words, word parts, and how segments are combined to create meanings.

Morpheme

The smallest unit of language that carries meaning.

Free Morpheme

Morphemes that can stand alone and carry meaning (e.g., shoe).

Bound Morpheme

Morphemes that must be combined with a free morpheme to be meaningful; cannot function independently (e.g., plural -s, prefix non-).

Derivational Morphemes

Bound morphemes (prefixes/suffixes) that can change one word into a different part of speech (e.g., happy to happiness).

Inflectional Morphemes

Bound morphemes that modify or add meaning to a free morpheme without changing its word class or overall meaning (e.g., shoes, jumped).

Emergence

When a child first begins to use a morpheme correctly.

Mastery

When a morpheme is fully acquired and used 90% of the time in obligatory contexts.

Obligatory Context

The section of an utterance where a morpheme is required for the sentence to be grammatically correct and meaningful.

MLU (Mean Length of Utterance)

A measure of utterance length based on the average number of free and bound morphemes in a sample of utterances; a moderate predictor of language complexity; fairly reliable until 4.0

Brown's Stage I

Age 12-26 months, MLU 1.0-2.0; primarily single-word utterances moving to early 2-word combinations ("telegraphic" speech).

Brown's Stage II

Age 27-30 months, MLU 2.0-2.5; utterances mark syntactic relations using word order (e.g., "Mommy eating").

Brown's Stage III

Age 31-34 months, MLU 2.5-3.0; emergence of simple sentences, yes/no and wh-questions, imperatives, and negatives.

Brown's Stage IV

Age 35-40 months, MLU 3.0-3.75; child begins clausal and phrasal embedding (e.g., "The boy, who smiled, spilled the milk").

Brown's Stage V

Age 41-46 months, MLU 3.75-4.5; syntactic modifications via compound sentences (e.g., "Mom dusted and I swept").

Wug Test

A study by Berko (1958) using nonsense words showing that children internalize a rule-governed morphological system rather than just imitating.

Literate Language

The formal style of language used in academics and textbooks, requiring more complex syntax and morphology than conversational speech.

Late Talkers (SELD)

Toddlers and preschoolers who demonstrate slower expressive language development without cognitive, sensory, or environmental deficits.

Specific Language Impairment (SLI)

Significant language learning difficulties in acquiring/processing syntax and grammar, despite the absence of hearing, cognitive, or emotional deficits.

Steps for calculating MLU

• Count the total # of free and bound morphemes in a spontaneous language sample of 50-100 utterances

• Divide the morpheme total by the # of utterances analyzed

• The # obtained is the MLU

Counts as one morpheme

Single words, compound words, proper names, auxiliary verbs, irregular past tense verbs (e.g., went, ate), irregular plurals

Counts as two morphemes

Possessive Nouns (Bob’s Book), Plural nouns, regular past tense

Exceptions / Specific rules for counting morphemes

• Do not count fillers (um, yeah, like)

• Assign two morphemes to non-negative contractions

• Assign two morphemes to negative contractions only if there is evidence that the child uses each part independently

Non-negative contractions

A shortened combination of a pronoun, noun, or question word with an auxiliary or copula verb (excluding the negative particle not), such as I'm, he's, you'll, she'd, or they're

Negative contractions

A shortened combination of a verb or auxiliary/modal with the negative particle not (ending in -n't), such as don't, can't, won't, isn't, or didn't

1-word utterances

Often involve a noun, verb, preposition, or other relational term

2-word utterances

Agent + Action (Mommy go) or Action + Location (Cara here)

3 main influences on later syntactic development

1. Exposure to written language

2. An increase in working memory capacity

3. New ways of relative language to thought