Cognitive Development

innate or learned?

Debated endlessly by philosophers and psychologists:

Nativists       ↔         Empiricists

Nature           ↔         Nurture

Heredity       ↔         Environment

Chomsky      ↔          Skinner

Language Development

Chomsky: it’s amazing that children can learn language at all

A portrait of Noam Chomsky that I took in Vanc...
Image via Wikipedia – Noam Chomsky

Two Analogies

(1) watching games of chess being played by a father and son who are both fanatics of chess. Not allowed to ask questions or anything. If you were sitting there just watching, could you learn the rules of chess in this way. One grandmaster claims to have learned this way because his parents thought it was too complex to explain.

(2) Watching a chess with errors being made but nothing being said. They will be semi-frequent and random. Could you learn the rules this way. You wouldn’t know if it was an error or a very rare move made in chess. Chomsky thought this was the sort of exposure that kids get with language.

Observational Evidence

Strong developmental regularities in language acquisition. All over the world, regardless of the environment, children learn language the same way: series of stages over time. The time required to move the stages varies but the order is invariant (unchanging).

Developmental milestones

Time Stage phenomenon
birth crying
6-8 weeks cooing repeating vowel sounds
6-12 months babbling consonants added
~12 months respond to simple words
12-18 months holophrastic one-word utterances

can say juice. Really means i want some juice but can’t say all of it yet. That’s what holophrastic means.

Nature vs. Nurture?

Nurture: exposure to language does affect the process. Time spent in each stage is variable

Nature: Invariant order.

Nativists’ position

Chomsky: invariant order suggests we are “hard wired” to learn language. Like walking.

Extreme form of this claim: there is a language acquisition device in the brain.

Experimental Evidence:

Infants can’t do much, so it’s hard to infer what they know

One cue, infants look at things that interest them

Another cue: sucking rate varies with attention (interested: rate speeds up; bored: rate slows down)

Eimas and Colleagues (1971)

Infants sucked on a pacifier that measures sucking rate.

Infants heard the sound /pa/ over a loudspeaker.

Initial interest, but as the sound repeats, sucking rate declines: habituation

At a certain point, the sound changes from /pa/ to /ba/

Small difference, but an important one in language. Infants as young as four months showed an increase in sucking rate

Later research pushed down to just one month.

Eimas’ study suggests that certain linguistic abilities are either inborn, or are learned at a very young age.

But later research showed that this was not unique to people:

chinchillas show the same pattern

Problem: observational data may not be conclusive

Another approach

Is there a critical period for learning language?

True for innate behaviors in other species: baby ducks imprinting (Lorenz) – when a baby duck hatches out of its egg, it will follow any large moving object in its vicinity. If imprinting does not occur shortly after birth, it will never occur.

If a person isn’t exposed to language early in life, can it be learned later? If it can’t be, then language learning may be innate.

Sources of evidence:

(1) feral children - children found in the wild who were apparently raised by wild animals.

very few documented examples. Developmental history of such children is unknown: perhaps they were abandoned because they seemed to be defective. Were they exposed to any language before they were abandoned or lost?

(2) neglected children – unfortunately, a few well-documented cases of this sort. Best known case: Genie, who was discovered in 1971 when she was 13.

Apparently Genie was exposed ot some language before the age of 20 months.

Hospital records show that she was normal and healthy at birth. Genie couldn’t speak when she was found, and had many other problems (malnutrition, motor problems, no social development).

A number of speech therapists worked with genie to help her develop language skills and she was able to acquire some language.

At age 18 (5 years after discovery) genies abilities were formally assessed. Her comprehension of language was quite good. But her mastery of syntax (word order) was quite limited…..and it was believed that she would never achieve fluency. Genie’s case seems to argue against a rigid critical period….but the amount of language she was exposed to in early life is still unclear.

and so nature vs nurture debate goes on

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