Chitra Bdr. Khatri kathmandu University, Kathmandu, Nepal

1. Critical Period Hypothesis (CPH)
in
Second Language Acquisition (SLA)
Presentation made by
Chitra Bdr. Khatri
Kathmandu University
03/10/2012

2. What is Critical Period Hypothesis?
• The critical period hypothesis is the subject of a
long-standing debate in linguistics and language
acquisition over the extent to which the ability to
acquire language is biologically linked to age.
• The hypothesis claims that there is an ideal
'window' of time in a person’s life to acquire
language in a linguistically rich environment, after
which further language acquisition becomes
much more difficult and effortful.

3. CPH Contd…
• The critical period hypothesis states that the
first few years of life is the crucial time in
which an individual can acquire a native
language (L1) if presented with adequate
stimuli.
• If language input doesn't occur until after this
time, the individual will never achieve a full
command of language especially grammatical
systems.

4. The Historical Background
• The critical period hypothesis was first
proposed by Montreal neurologist Wilder
Penfield and co-author Lamar Roberts in
1959.
• Popularized by Eric Lenneberg in 1967
with his famous book Biological
Foundations of Language.

5. Historical Background Contd…
• Lenneberg proposed that brain lateralisation (the
longitudinal fissure that separates the brain into
two distinct cerebral hemispheres) at puberty is
the mechanism which closes down the brain's
ability to acquire language.
• Another well-known person who supports the
critical period hypothesis would be Noam
Chomsky, who believes that children are born
with an inherited ability to learn any human
language.

6. History of CPH Contd…
• Chomsky: every child has a ‘language
acquisition device’ or LAD which encodes the
major principles of a language and its
grammatical structures into the child’s brain.
• Lenneberg: there are maturational constraints
on the time a first language can be acquired.
• If language acquisition does not occur by
puberty, some aspects of language can be
learnt but full mastery cannot be achieved.

7. One Test related to CPH in SLA
• Tested by comparing the English proficiency
attained by 46 native Korean or Chinese
speakers arrived in the US between the ages
of 3 and 39, and who had lived in the US
between 3 and 26 years by the time of testing.
• Tested on a wide variety of structures of
English grammar, using a grammaticality
judgment task.

8. Outcome of the Experiment
• Test analyses demonstrated a clear and strong
advantage for earlier arrivals over the later
arrivals.
• Test performance was linearly related to age
of arrival up to puberty.
• After puberty performance was low but highly
variable and unrelated to age of arrival.

9. Outcome Contd…
• This age effect was shown not to be an
inadvertent result of differences in amount of
experience with English, motivation, self-
consciousness, or American identification.
• The effect also appeared on every
grammatical structure tested.
• The results support the conclusion that a
critical period for language acquisition extends
its effects to second language acquisition.

10. Further Supportive Studies

11. The story of Genie, a thirteen year girl, who was a victim of child abuse.
Genie was a thirteen-year-old victim of lifelong child abuse. She had been kept
strapped to a potty chair and wearing diapers. She appeared to be entirely
without language when she was found at he age of 13. Her father had judged
her retarded at birth and had chosen to isolate her, and so she had remained
until her discovery.
It was an ideal opportunity to test the theory of CHP on her. The experiment
proved that she was unable to acquire language completely.

12. Isabella under training and care
Isabelle, a girl, who was incarcerated with her deaf-mute mother until
the age of six and a half (pre-pubescent). She also had no language
skill, but unlike Genie, she quickly acquired normal language abilities
through systematic specialist training.

13. Supports in Favour and Against
of the CHP

14. Supports in favour of the CPH:
• Loss of neural plasticity in the brain with age.
• Loss of access to the language learning faculty.
• Maladaptive gain of processing capacity with
maturation.
• A "use it then lose it" philosophy and a "use it or lose
it" philosophy.
• The idea that learning inhibits learning.
• Study on native Korean and Chinese speakers found
that the earlier (in age) that the non-native English
speakers had come to the US, the better their English
proficiency was. Also, speakers who had arrived prior
to puberty had the highest levels of proficiency.

15. Supports against the CPH
• Krashen's Theories of language acquisition
provide alternate hypotheses to explain
second language acquisition. (He discussed
five different hypotheses: natural
order, acquisition/learning, monitor, input
and affective filter)
• Statements supporting CPH misinterpret
the facts and, in turn, ignore the findings
that older learners acquire a second
language more quickly and efficiently.

16. Supports against the CHP Contd…
• The idea that neurological differences in
children and adults are misattributed to
differences in second language acquisition and
proficiency.
• Although it is understood that these
differences exist, there is not substantial
proofs that they cause differences in second
language acquisition.

17. Support against the CHP Contd…
• Undeserved emphasis on unsuccessful adult
second language learners, and too little
emphasis on older learners who achieve
native level proficiency in a second language.
• Problems in second language testing.
• The role of the learning environment.
• The role of learner motivation.

18. Conclusition
• My belief: after reviewing data on both sides of
the controversy, I believe that critical period in
second language acquisition is not relevant to
proficiency level attainment.
• Though I explained some studies in favour of the
existence of CPH, I think that there are too many
variables with strong factual support that explain
second language acquisition differences in
learners, and too few factual explanations of the
critical period theory to warrant its belief.
• However, due to the relatively recent forays into
explaining cognition neurologically, it is possible
that future research could yield more substantial
support for the critical period hypothesis.

19. Conclusition Contd…
• I also feel that the study of second language
acquisition would greatly benefit from additional
studies examining all possible variables that
result in different second language proficiency.
• Finally, it is my hope that my colleagues who
wish to tackle a second language will not
dissuade by the prospect of a critical period being
passed, because there is just not enough factual
evidence to support it at this time.

20. That’s all for Today!
Thank you for the patience.