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Nature vs. Nurture: Theory of Language Acquisition
Some Background: History of Psycholinguistics
Behaviorism (early to mid twentieth century)
Early 1900s, behaviorists tried to establish psychology as an empirical science with
scientific methods but devoid of mental constructs like mind, thought, and imagery.
B.F. Skinner in Verbal Behavior (1957) argued that speech was a product of operant
learning processes such as reinforcement, extinction and generalization.
Linguistics (post behaviorism through Chomsky) - nature vs. nurture debate
Noam Chomsky critically reviewed Skinner’s book in 1959; gave rationalist argument that
the potential for language was an innate mental capacity. Chomsky argued that children’s
patterns of language acquisition were too systematic to be the product of parents’ operant
conditioning. Human species has a built-in language acquisition device (LAD).
Theories of Language Acquisition
1. Imitation: children learn language just by imitating adult language i.e. learn
language by simply hearing and copying what they hear (Criticism: differ from
adult speech, mistakes, failure to reproduce, rich knowledge of rules)
2. Learning Theory (reinforcement and conditioning): children learn language
because parents reward proper uses and discourage improper uses (Criticism:
ungrounded; failure in trying to correct improper uses)
3. Innatist Theory: for various reasons, language must be genetically encoded
(biologically pre-programmed)
Terms:
 Universal Grammar: The core of the grammar that is universal to all languages, and
which specifies and restricts the form that individual languages can take.
 Language acquisition device (LAD): Chomsky argued that children hear an
impoverished language input and therefore need the assistance of an innate
language acquisition device in order to acquire language.
 Principles and Parameters
o Principles: cross-linguistically invariant properties of syntax common to all
languages; Account for linguistic universality (e.g. structure dependency,
projection principle)
o Parameters: Possible variables in the instantiation of principles; Account for
cross-linguistic syntactic variation (e.g. head parameter, pro-drop parameter)
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Examples of pro-drop parameters across different languages
English
Italian
Arabic
non-pro-drop
pro-drop
pro-drop
Chinese
German
French
pro-drop
non-pro-drop
non-pro-drop
subject-verb
he speaks
lui parla
huwa
yatakallamu
ta shuo
er spricht
il parle
null subject
*speaks
parla
yatakallamu
shuo
*spricht
*parle
Verb-subject inversion
*speaks he
parla lui
yatakallamu
huwa
*shuo-ta
*spricht er
*parle il
Arguments for nativism: evidence from child language acquisition
1. Logical puzzle (Bertrand Russell, 1948): “How comes it that human beings, whose
contacts with the word are brief and personal and limited, are nevertheless able to know
as much as they do know?”
2. Convergence of grammar (individually different exposure to language as a child but a
converged grammar as an adult, i.e. different experience, same grammar)
3. Early emergence of complex linguistic ability (gap between general cognitive
development and linguistic development)
4. Speed of acquiring linguistic knowledge
Phonological Development
1. Speech perception
 Research techniques: sucking habituation paradigm (or high-amplitude sucking
procedure), and head-turning procedures
 Speech sound vs. Non-speech sound distinction: children are sensitive to speech
sounds from birth
 Phonetic distinctions: between 1 – 4 months of age, infants are sensitive to all the
acoustic differences (voicing, manner and place of articulation)
 Phoneme distinction: (related to phonetic distinction ability of infants), infants
have highly sensitive level of discrimination of speech sounds, and thus they can
discriminate phonemes not only of their mother tongue but also of other languages;
Native language magnet mode (Kuhl, 1993)
 Categorical perception: /ba/ and /pa/ distinction (skip now; will be mentioned later
in speech perception)
 Chinchillas’ categorical perception of /da/ and /ta/ in the same way as humans do
2. Speech production
 Babbling (6 – 10 months): reduplicated babble (repetition of CV pattern, e.g.
babababababa) and non-reduplicated (or variegated babble, e.g. bamido, bigodabu)
 Role of babbling: continuity vs. non-continuity hypotheses make different
assumptions on the role of babbling as a direct precursor of language (however, in
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general, babbling can be a form of play where various sounds are practiced whether
or not they are sounds of a specific language)
Gap between perception and production: their perception is advanced than their
production ability.
Child: Where is Mytul?
Adult: You mean Mytul?
Child: NO, Mytul!
Adult: Oh, Michael?
Child: Yes, Mytul.
Lexical Development
1. Some facts:
 around 10 ~ 12 months: produce first words
 ~ 18 months: produce one word at a time (holophrase)
 18 months: produce simple multiword combination
 by age 6 years: 14,000 words (8.64 words a day)
2. Mapping Problem
 Mapping problem in an ostensive model of word learning (pointing and naming)
 Whole-object hypothesis: a novel label is likely to refer to the whole object and not
to its parts, substance, or other properties
 Taxonomic constraint: extending objects’ labels to other objects, i.e. labels refer to
objects of the same kind rather than to objects that are thematically related (thematic
relation: who-did-what-to-whom relation) Most simply, the taxonomic constant is
that a word (e.g. “dog”) refers to a category of similar things (e.g. “cat”) rather than
to the thematically related objects (e.g. “dog food”).
o Criticism: there are many counter examples (in fact, children are interested
in thematic relations of objects)
 Mutual exclusivity assumption: constrain word meanings by assuming at first that
words are mutually exclusive (that each object will have one and only one label);
helps children override the whole object assumption, thereby enabling them to
acquire terms other than object labels (Q: dog, pet, poodle?)
3. Errors in the early representation of meaning
 Over-extensions: a child uses a word in a broader way than the adult usage
 Under-extensions: children use words more specifically than their meaning
4. Syntactic Bootstrapping
Children use their syntactic knowledge to learn the meanings of a new word.
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Syntactic Development
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MLU (Mean Length of Utterances in morphemes): a measure of syntactic growth
Holophrase stage (one-word stage): single-word sentence, use environment as the
rest of the sentence
Telegraphic stage (two-word utterances): basic word-order knowledge; leave out
function words; lack inflection indicating number, gender, tense; pivot grammar
Research methods:
o Interview (data collection in natural setting)
o comprehension study: eye gazing; the intermodal preferential looking
paradigm (visual and auditory modes); task elicitation
o production study: utterance elicitation
(based on various studies) Children’s syntactic knowledge seems to show a gap
between from comprehension and production (their comprehension appear to be in
advance of their production)
Semantic bootstrapping: using the semantics to predict the syntax
o Agent-Action
Daddy hit
o Action-Object
hit ball
o Agent-Object
Daddy ball
o Possessive
Daddy chair
o Action Locative
go store
o Entity Locative
book store
Morphological Development
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Grammatical morphemes begin to appear when MLU = 2.5
U-shaped development (went – goed – went)
productivity (a wug test: “This is a wug. This is another one. Now there are two ___.”)