Lexical Development II: Word spurt Aylin Küntay Language and Communication Disorders Meeting 3

To know a word means To link word (sound sequence) with meaning or concept Symbol: refers to or stands for something Quine’s induction problem: when someone point to a rabbit and say ‘rabbit’ how do you know the word refers to the animal and not the action of the rabbit or characteristics of the rabbit (white, fast, fluffy, big, etc.) GAVAGAI PROBLEM

The very beginning of words Around 10-18 months. Are they ‘true’ referential words? Many first words are context bound, situational, for e.g., doggie refers to dog sticker by the child’s bed A word that is context bound for one child may be referential for another Context bound usages are usually most frequent use by caregivers Perhaps context bound words are not true words; we can talk about a prelexical stage of word learning But some children’s first words are referential Nelson: referential vs. expressive children

Acquisition of first 50 words Slowly adding words until 18 months (range: 14-24 months) Add 8-10 per month, and sometimes new words do not stay around Once the child knows 50-100 words, the rate of word learning increases to around 40 words per month

Vocabulary spurt: Universal? Some studies suggest no Others suggest yes, but just occurs later (e.g., after the 50 word period)

Causes of vocabulary spurt Ability for fast mapping Could you please get the caponata? Mervis & Bertrand: 4 familiar objects (ball, shoe, car, doll) and garlic press. Give me the shoe vs. give me the dax Children who fast mapped had larger vocabs Naming insight. All things have names (Helen Keller) Cognitive changes Social skills development

Cognitive changes and vocabulary spurt Nelson: change from analyzing experiences to things Gopnik: development of categorization. Strong correlation between vocabulary and spontaneous two-category sorting 15 months: pick dolls, leave cars 18 months: make 2 piles of dolls and cars

Individual differences in rate of lexical development Macarthur CDI. 16 months produce between 0-116. 24 months produce 50-500. Huge variability Child factors Environmental factors

Child features influencing rate Phonological memory At 4 years, children with bigger phonological memories learn more words even when controlled for IQ and vocabulary size Sex differences (tiny difference): female advantage Girls mature faster Structural differences in brain Caregivers talk more to girls

Environmental influences More talk leads to more words SES: Hart & Risley. Small effect but increases with time. Birth order. First borns reach 50 word mark earlier But no difference at 100th word mark

Baldwin: interpersonal understanding Importance of social interaction and interpersonal understanding vs. Importance of salience (general cognitive constraints) Evidence for importance of social interaction Young typical babies Autistic children

For Thursday Simple sentences and Complex Syntax, Chapter 6 and Chapter 7 of How Babies Talk