Language
is a cognition that truly makes us human. Whereas other species do communicate
with an innate ability to produce a limited number of meaningful vocalizations
(e.g. bonobos), or even with partially learned systems (e.g. bird songs), there
is no other species known to date that can express infinite ideas (sentences)
with a limited set of symbols (speech sounds and words).
This
ability is remarkable in itself. What makes it even more remarkable is that
researchers are finding evidence for mastery of this complex skill in
increasingly younger children. Infants as young as 12 months are reported to
have sensitivity to the grammar needed to understand causative sentences (who
did what to whom; e.g. the bunny pushed the frog (Rowland & Noble, 2010).
After
more than 60 years of research into child language development, the mechanism
that enables children to segment syllables and words out of the strings of
sounds they hear, and to acquire grammar to understand and produce language is
still quite an enigma.
Early
Theories
One
of the earliest scientific explanations of language acquisition was provided by Skinner (1957).
As one of the pioneers of behaviorism, he
accounted for language development by means of environmental influence.
Skinner
argued that children learn language based on behaviorist reinforcement
principles by associating words with meanings. Correct utterances are
positively reinforced when the child realizes the communicative value of words
and phrases.
For
example, when the child says ‘milk’ and the mother will smile and give her some
as a result, the child will find this outcome rewarding, enhancing the child's
language development (Ambridge & Lieven, 2011).
Universal
Grammar
However,
Skinner's account was soon heavily criticized by Noam Chomsky, the world's most
famous linguist to date. In the spirit of cognitive revolution in the 1950's,
Chomsky argued that children will never acquire the tools needed for processing
an infinite number of sentences if the language acquisition mechanism was
dependent on language input alone.
Consequently,
he proposed the theory of Universal Grammar: an idea of innate, biological
grammatical categories, such as a noun category and a verb category that
facilitate the entire language development in children and overall language
processing in adults.
Universal
Grammar is considered to contain all the grammatical information needed to
combine these categories, e.g. noun and verb, into phrases. The child’s task is
just to learn the words of her language (Ambridge & Lieven). For example,
according to the Universal Grammar account, children instinctively know how to
combine a noun (e.g. a boy) and a verb (to eat) into a meaningful, correct
phrase (A boy eats).
This
Chomskian (1965) approach to language acquisition has inspired hundreds of
scholars to investigate the nature of these assumed grammatical categories and
the research is still ongoing.
Contemporary
Research
A
decade or two later some psycho linguists began to question the existence of
Universal Grammar. They argued that categories like noun and verb are
biologically, evolutionarily and psychologically implausible and that the field
called for an account that can explain for the acquisition process without
innate categories.
Researchers
started to suggest that instead of having a language-specific mechanism for
language processing, children might utilize general cognitive and learning
principles.
Whereas
researchers approaching the language acquisition problem from the perspective
of Universal Grammar argue for early full productivity, i.e. early adult-like
knowledge of language, the opposing constructivist investigators argue for a
more gradual developmental process. It is suggested that children are sensitive
to patterns in language which enables the acquisition process.
An
example of this gradual pattern learning is morphology acquisition. Morphemes
are the smallest grammatical markers, or units, in language that alter words.
In English, regular plurals are marked with an –s morpheme (e.g. dog+s).
Similarly, English third singular verb forms (she eat+s, a boy kick+s) are
marked with the –s morpheme. Children are considered to acquire their first
instances of third singular forms as entire phrasal chunks (Daddy kicks, a girl
eats, a dog barks) without the ability of teasing the finest grammatical
components apart.
When
the child hears a sufficient number of instances of a linguistic construction
(i.e. the third singular verb form), she will detect patterns across the
utterances she has heard. In this case, the repeated pattern is the –s marker
in this particular verb form.
As
a result of many repetitions and examples of the –s marker in different verbs,
the child will acquire sophisticated knowledge that, in English, verbs must be
marked with an –s morpheme in the third singular form (Ambridge & Lieven,
2011; Pine, Conti-Ramsden, Joseph, Lieven & Serratrice, 2008; Theakson
& Lieven, 2005). Approaching language acquisition from the perspective of
general cognitive processing is an economical account of how children can learn
their first language without an excessive biolinguistic mechanism.
Conclusion
However,
finding a solid answer to the problem of language acquisition is far from being
over. Our current understanding of the developmental process is still immature.
Investigators of Universal Grammar are still trying to convince that language
is a task too demanding to acquire without specific innate equipment, whereas
the constructivist researchers are fiercely arguing for the importance of
linguistic input.
The
biggest questions, however, are yet unanswered. What is the exact process that
transforms the child’s utterances into grammatically correct, adult-like
speech? How much does the child need to be exposed to language to achieve the
adult-like state?
What
account can explain variation between languages and the language acquisition
process in children acquiring very different languages to English? The mystery
of language acquisition is granted to keep psychologists and linguists alike
astonished a decade after decade.