Language Developmental Milestones

What is the prelinguistic period of language development?

0-15 months

What is the emerging language period of language development?

16-36 months

What is the typical sequence of language development during the first year of life?

joint attention → gestures → words

What qualifies as an intentional communication act?

Must be adult directed, intended effect of influencing adult’s behavior, persisting if adult fails to respond in intend way

What type of communication functions do you expect to observe during the prelinguistic period?

Request, protests, rejections, comments

What is the receptive phonological developmental sequence during the first year in typical children?

25th week of gestation

• hear sounds

1 month

• detects prosodic, phonemic categories

2 months

• detects utterance boundaries in connected speech

What is the expressive phonological developmental sequence during the first year in typical children?

0-2 months

• vegetative sounds

2-4 months

• cooing, laughing

4-6 months

• quasi-resonant nuclei, vocal play

6-10 months

• canonical, reduplicated babbling - CV syllables intonation contours

What is the receptive vocabulary size of a typical 8-12 month old?

3-50 words

What does a child need to know to understand a word?

phonological shape, conceptual meaning, morphosyntactic features

How many communicative acts does the typical 8-12 month old make per minute during free play?

2.5

What do intentional communication behaviors look like between 8-12 months?

Preverbal intentional communication using gaze, gesture, and vocalization

What proportion of communication attempts are socially interpretable at 14 months of age? Speech?

67% socially interpretable, 41% with interpretable speech acts

How many conversation turns are expected between an average developing 14 month old and their communication partner?

3-5 interchanges

What is the gestural production at 15 months predictive of?

First word use, language development

What are the 3 categories of gesture production?

Dietic, symbolic, representational

What is the receptive language vocabulary size of a typical 15 month old?

Up to 50

What is the expressive language vocabulary size of a typical 15 month old?

Up to 10

How many communicative acts does the typical 18 month old make per minute during free play?

2

What is the phonological inventory of a typical 18 month old?

18-36 months

• p, m, h, n, w, b

24-48 months

• k, g, d, t, ng

What syllable shapes are you likely to observe in a typical 18-month-old?

CV shape, 1 syllable; some reduplicated words (/baba/) closed syllables emerge (CVC)

How intelligible is the speech of a typical 18-month-old?

25-50% to familiar speakers

What proportion of communication attempts are socially interpretable at 20 months of age? Speech?

90% socially interpretable, 80% with interpretable speech acts

How many conversation turns are expected between an average developing 20-month-old and their communication partner?

4-6 interchanges

How many communicative acts does the typical 24-month-old make per minute in free play?

5-7

What is the approximate receptive and expressive vocabulary size of a typical 24-month-old?

up to 150-300 words

When do typically developing children begin making two-word combos?

After acquiring expressive vocab 50-100 words, 18-24 months

What is an example of an early emerging semantic relation?

Agent, action, object combos, possession, location, attributes

At 24-months what MLU in morphemes is a “red flag” for language delay?

less than 1.5

What morphological structures do you expect a 2.5 year old to make?

Brown stages II: present progressive (-ing), in, on, regular s-plurals

What proportion of communication attempts are socially interpretable at 32 months of age? Speech?

98% socially interpretable, 97% with interpretable speech acts

How many conversation turns are expected between an average developing 20-month-old and their communication partner?

5-7 interchanges

How intelligible is the speech of a typical 36 month old?

50-70%

What is the approximate mean utterance length in words produced by a typical 36 month old?

3-5

What are the five levels of symbolic play?

Pre symbolic, Auto symbolic, Single-scheme symbolic, Combo symbolic games, Hierarchical pretend