Age and Language Acquisition

Language Acquisition and the age

LA studies suggest that kids are “built to learn language” in a way that adults are not.

Perhaps there is a “sensitive period” early in life where one absorbs languages? A sensitive period which ends at some point…

The Critical Period Hypothesis

Lenneberg 1967

Lenneberg 1967 (or Penfield and Roberts 1959) is usually considered to be the written origin of this idea that there is a “critical period” or “sensitive period” for language acquisition.

He based this on several observations, including the observation that critical periods are biologically common.

The Critical Period HypothesisThe Critical Period Hypothesis

– This hypothesis states that there is only a small window of time for a first language to be natively acquired.

– If a child is denied language input, he/she will not acquire language

THE CRITICAL PERIOD HYPOTHESIS

Critical period: a biologically determined period of line when language can be acquired more easily and beyond which time language is increasingly difficult to acquire.

Eric Lenneberg (1967) argued that the LAD, like other biological functions, works successfully only when it is stimulated at the right time – a time which is referred to as the critical period‟

There are two versions of the CPH:

1. The strong version suggests that children must acquire their first language by puberty or they will never be able to learn from subsequent exposure.

2. The weak version is that language learning will be more difficult and incomplete after puberty.

The Critical Period Hypothesis (CPH) claims that there is such a biological timetable.

Initially the notion of a critical period was connected only to first language acquisition.

Critical period or critical periods?

The basic claim

- strong and weak versions

Evidence for L1: feral children

L2: learning and acquisition

Critical & sensitive periods

Other biologically determined deadlines: - imprinting: chicks & ducklings follow first thing they see

(it’s likely their mommy)

- visual cells in humans: if cells for both eyes don’t receive visual input during the first year or so of life, they lose the ability to respond to visual input

“sensitive period”: biologically determined period during which learning must occur for development to happen correctly, but development can still occur partially after this period

Critical & sensitive periodsHow do we test for a critical/sensitive period for language

acquisition?

Critical & sensitive periodsHow do we test for a critical/sensitive period for language

acquisition?

Ideal experiment: deprive children of all linguistic

input during the purported critical period and see

how language development occurs.

Problem: ideal experiment isn’t so ideal ethically or logistically

Critical & sensitive periods

Some historical cases that have unintentionally

provided lack of linguistic input to children:

Problem: the lack of language may be due to other reasons

Wild Peter (13/1724)Victor (11/1800)Kaspar Houser (16/1828)Kamala and Amala (18m., 8/1920)

Feral children

Socialising, teaching and observing

Problems- ethical experiments?

- teacher=researcher bias

- relation between lack of language and mental + social retardation

Critical & sensitive periods How do we test for a critical period for language

acquisition?

A more thorough study: Genie

Critical & sensitive periods How do we test for a critical period for language acquisition?

Genie

1970s: 13-year-old Genie brought by her mother to social services after escaping mentally ill father; until mother’s escape, had no language input (and very horrific living conditions)

By age 17, she had a 5-year-old’s vocabulary, and could express meanings by combining words together.

Genie

Severe social isolation

Thought to be mentally retarded

Punished for speech 20 words,

colours,”stoppit”, „nomore”

Research and socialisation

Taken into care The first year: HOPE- plural and singular nouns, - positive and negative sentences - 2/3-word sentences.

Later: slow-down Four years later- No negation- 'No' + V + Object - No proper questions

"Where is may I have a penny?"

"I where is graham cracker on top shelf?"

Confused her pronouns, 'you' and 'me' interchangeable

'Hello‘, 'Thank you‘'Stopit‘, 'Nomore' addressed to

herself

Critical & sensitive periods

However…syntactic skills lagged far behind - deficient in both production and comprehension.

“Mama wash hair in sink.” “Like go ride yellow school bus.”“At school scratch face.” “Father take piece wood. Hit. Cry.”“I want Curtiss play piano.” “Applesauce buy store”“Man motorcycle have.” “Father hit Genie cry long time ago.”

Dichotic listening tasks showed language was a right-hemisphere activity for her.

Support for CPH?

Severe neglect and emotional trauma Possibility of mental retardation Right-hemisphere dominance Language not lateralised to left-hemisphere:

cause or result?

Critical & sensitive periods How do we test for a critical period for language

acquisition?

One success story for lack of linguistic input with a young child: Isabelle

1930s: 6-year-old Isabelle discovered hidden away in a dark room with a deaf-mute mother as her only contact.

She was taught to speak and by age 8, appeared to be normal. Potential implication:

Isabelle discovered before critical period was over.

Critical & sensitive periodsHow do we test for a critical/sensitive period for language acquisition?

Another study: Chelsea (Curtiss 1988)

Family background: A partially deaf woman incorrectly diagnosed as “retarded”. From a loving home.

Discovered at age 31, and fitted with hearing aids

Outcome: Learned a large vocabulary, but syntax and morphology worse than Genie.

Evidence from the deaf

'Chelsea- First diagnosis: retardation- Warm, supportive family, search for help- At 31: diagnosed to be deaf- IQ levels for a normal 10 year old- Works at a vet’s, reads, writes,communicates- Strings of words, with no syntactic structure- Utterances comprehensible in context

Critical periods

Sample speech from Chelsea:

(1)The small a the hat

(2) Orange Tim car in

(3) I Wanda be drive come

(4) Breakfast eating girl

(5) They are is car in the Tim

Evidence from neurology

Medical evidence Right hemisphere compensates for language

capacity in childhood No such compensation in adulthood

Critical & sensitive periods How do we test for a critical period for language acquisition?

Late acquisition of sign language (ASL):

deaf-of-hearing children whose parents don’t know sign language. Children are eventually exposed to sign language when they encounter other deaf children.

Critical & sensitive periodsHow do we test for a critical/sensitive period for language

acquisition?

If critical or sensitive period is true, children who learn from infancy should be better than children who learned later – this is what Newport (1990) found. Children who were 4-6 when first exposed were far superior in their sign language ability to children who were exposed after age 12.

Critical & sensitive periodsHow do we test for a critical period for language acquisition?

Also important: not just about how long sign language speakers had known the language. Speakers who had been signing for more than 30 years showed this same difference: those exposed younger were far superior in their language skills to those exposed when they were older.

Evidence from sign language

Native – clear advantage in the use of grammatical markers

Early starters Late starters

Conclusion

Is there a CPH in LA?- Clear neurological evidence- Suggestive evidence from the deaf- Feral children - inconclusive