Seminar slides based on Johnson&Newport (1989), Newport(1990) and DeKeyser (2000)

1. The case for critical period
in second language acquisition
LAP seminar, 28th October
presented by Takashi Oba

2. Today’s focus
Are age of onset (arrival) and L2 grammatical ultimate
attainment systematically related?!
- Does CP really exist in L1? (Newport, 1990)!
- Does maturational constraints affect L2 ultimate grammar performance?!
(Johnson&Newport, 1989; DeKeyser, 2000)

3. Critical Period Hypothesis and
maturational constraints
Critical Period Hypothesis (CPH): “a maturational time period!
during which some crucial experience will have its peak effect!
on development or learning, resulting in normal behavior!
attuned to the particular environment to which the organism!
has been exposed.” (by E. Newport)!
!

4. Language learning and maturational
constraints
• Language acquisition occurs under maturational!
constraints, operating successfully only during a!
maturationally bounded period!
• Given similar input, learners in different maturational!
states do not achieve the same outcome

5. What is the underlying mechanism in maturational
constraints on language learning? !
- Why are children successful language learners? !
!
- Why are adults, having better capabilities than children at
most things, not?!
!
- What causes the gradual decline in language acquisition
over maturation?

6. Biologically-driven CP (Lenneberg, 1967)
• Language learning occurs exclusively within childhood!
!
• Maturational change mechanism: !
- neurological change in nature!
- the brain loose plasticity and reorganizational capacities!
necessary for language learning !
• Maturational constraints do present from birth and the
special language faculty will be intact and decay as
maturation continues!
• Maturational constrains are independent of other cognitive
abilities

7. “Less is More” hypothesis (Newport, 1988)
• Language learning declines over maturation because
cognitive abilities increase!
• Children and adults differ in their abilities to accurately
perceive and remember complex stimuli!
• Whereas children perceive and store only component
parts of the complex linguistic stimuli, adults more readily
perceive and remember the whole complex stimuli !
• Children is a better position to locate the componential
units of language

8. CPH & second language (L2) acquisition
The exercise hypothesis The maturational hypothesis
L1 children >> adults children >> adults
L2
children ≒ adults
(adult >children)
children >> adults
Maturational
constraint in
L2
No
(if capacity is activated!)
Yes
(language faculty decay early in life)

9. Other variables??

10. - Social educational factors
(Jia & Aaronson, 2003, Flege et al, 1999)
!
- Cognitive variables (Hakuta, Bialystok, & Wiley, 2003)
!
- Prior learning itself, processing of L1 input
(Baker et al, 2008; McCandliss et al, 2002),
!
- Memory system: declarative/explicit & procedural/implicit
memory (Trofimovich, Martin-Chang, & Levesque, 2013)

11. Age of onset
(arrival)
motivation
identification
self-consciousness
Ultimate
performance of L2
grammar
Exposure
length
Beginning of
instruction
amount of
initial exposure
validity of
measurement
biologically-driven
maturational
constraints
L1
influence
input
processing
WM
system

12. Empirical studies
• Maturational constrains on L1 late learners:!
- Newport&Supalla (1987); Newport (1990): In learning signed language in!
deaf children, there was a decline over age in the ability to acquire!
L1(signed language)!
!
• Research on age effects on L2 acquisition: !
(1) Early stage of L2: adults learn L2 quickly but the advantage is short-lived !
- phonology (Olson & Samuels, 1973) !
- syntax (Snow & Hoefnagel-Hohle, 1978) !
(2) Eventual attainment : superiority for children* !
- phonology (Asher & Garcia, 1969; Oyama, 1976) !
- syntax (Oyama, 1978; Patkowski, 1980)!
!
＊ Rate advantage of adults disappears as children catch up and !
surpass late starters (Long,1990; Aoyama et al, 2008)!
!

13. Newport (1990)
Goal of the study:
Test effects of CPH (maturational constrains) on L1
acquisition by looking at deaf children with different initial
ages of exposure to American Sign Language (ASL)

14. Method
Participants:
- Deaf children born to hearing parents!
- ASL proficiency in people exposed to ASL for at least 30 years as!
their primary language!
!
Measurement:
- Tested on various production and comprehension tasks!
G1: exposure since birth!
G2: exposure since school (age 4-6)!
G3: exposure after age 12!
- Tested structures:!
(1) word order; agreement between subject, object & verb; !
(2) verbal classifiers and associated motion morphemes; !
(3) verb inflection for aspect and numbers; !
(4) derivational morphemes distinguishing related nouns and verbs!
!

15. Result 1 No age effect !
4~6 12~

16. Result 2
> >
Significant
effect of age on
L1 morphology
r*= -.6 ~ -.7
4~6 12~

17. How early is early enough?
• Newport & Supalla’s (1987) study of ASL as L1 among!
congenitally deaf individuals, who started learning ASL at!
different ages.!
!
- Exposure before 6 yields native competence, uniform error types
(4-6 did slightly less well).!
- Exposure after 7 yielded more errors in closed-class items, later
correlated with evidence of more “holistically” (rote) learned
elements.!
- Exposure after 12 much higher error rate and variable error
types, more frozen forms.!

18. Differences in use of morphemes
• Native learners show consistent response patterns
• Late learners show some usage of the same forms, they also
show ungrammatical usage
- Frozen lexical items (whole-word signs)
- Highly variable in morphology
- Omission of morphemes

19. Conclusion: Evidence for CP in L1 acquisition
• Maturational constrains do exist in late L1 learners !
• The age effects are not associated with length of experience
with language. All subjects had at least 30 years of everyday
experience!
!
• Delayed first language acquisition is incomplete when the
onset of language is after age 4!
→ the later the age of onset, the less complete acquisition!
is likely to be!
!

20. Extended to L2 acquisition?
• There is some kind of advantage to L1A within the!
“critical/sensitive period”!
!
• Once you get L1 within the CP, is that good enough (does!
that “get it started”) for L2A even after the CP?!
!
• Does maturational function (CP) affect L2?!
- Is it easier to learn an L2 inside the critical period?!
- It is possible to learn an L2 outside the critical period?!
!
!

21. Johnson & Newport (1989)!
Goal of the study:
Aiming to test whether the critical period hypothesis occurs
at L2 learning by looking at correlations between eventual L2
grammatical performance and age of initial exposure to the
target language.!
!
!
Is CPH a phenomenon exclusively seen in L1 acquisition or does it
influence on ultimate performance in L2 grammar acquisition? !
!

22. Research questions
Q1 Is there an age-related effect on learning the grammar of
a second language?
Q2
If so, what is the nature of this relationship? What is the
shape of the function relating age to learning and ultimate
performance, and where (if anywhere) does the relationship
plateau or decline?
Q3
Can experimental or attitudinal variables, separately or
together, explain the effects obtained for age of learning?
Q4
What areas of grammar are the most and least problematic
for learners of different age groups?

23. Method
J&N (1989)
Participants # 46 Korean & Chinese
age of arrival range 3-39
socio-economic
status
homogeneity (college student&faculty
members
length of residence
at least 5 yrs
(av. 9.8-9.9 yrs)
Measurement Grammatical Judgement (GJ) test
item # in GJT 276

24. Method (cont.)
•Grammatical Judgement (GJ) test:
- 276 sentences involving 12 different rules of English grammar
- Hear recorded pairs of sentences and judge grammatical (136)
or ungrammatical (146)
- Ex. (1a) The farmer bought two pigs at the market.
*(1b) The firmer bought two pig at the market.

25. Results
1. Age of acquisition (AA) and ultimate performance
Age of Arrival & GJ
test score→significantly
related!!
(earlier is higher)
r=-.77, p<.01
> > > >

26. 2. AA before vs. puberty
＊
During Maturation
Decline in ability with maturation.
After Maturation
No relationship between Age of
Arrival and Test Score
ns
Age of arrivals makes difference
before 15 yrs !
Large variance
→Individual differences
significant decline
began!
Early arrival Late arrival

27. • Early arrivals divided further: 3-7yrs, 8-10 yrs, 11-15 yrs!
!
- No difference in performance between native speakers!
subgroup1 (3-7 yrs)!
→Children immersed in an L2 before 7yrs will be able to!
achieve native-like fluency; !
→Children 7+ yrs show a decline in overall performance.!

28. 3. Experimental attitudinal variables
None of the correlations
are significant
Benefits of early
classroom exposure, like
immersion?

29. • Attitudinal variables were more adversely affected when age
of arrival was partialled out (age of arrival = independent
variable) ??!
• “…apart from whether attitudinal variables do or do not play
a role, there is a clear independent effect of age of arrival
on ultimate performance” !

30. - In addition to effects of age of arrival, self-consciousness
identification must be taken into account as crucial factors of
age effects influencing on L2 attainment (particularly for adults)!
!
- Independent of any possible attitudinal effects, age of arrivals
has an effect on L2 learning !
!
- Overall, non-maturational explanation, experimental and
attitudinal variables, for the age effects may not be fully
supported

31. 4. Age of arrival (late learners) rule type
Errors↑
Errors↓
-Two-way ANOVA for late learners: 17-24 yrs 25-39 yrs
-Significant interactional effects between rule type and age on widely
varied rule types !
-Late learners tend to made more errors for some types, but very few
for others (less randomized)

32. Conclusion: Evidence for CP in L2 acquisition
• Support the maturational state hypothesis!
!
• Nature of relationship between age of arrival and performance!
- Early arrival learners ( 7 yrs) achieved native-like fluency !
- A Linear decline in performance up through puberty (after 7 yrs) !
- A Subsequent lack of linearity and great variability after puberty !
(after 16 yrs)!
!
• Adult learners (after puberty)
- Quite a few grammar can be learned by adults (except
“determiners””plurals”), but great variability of errors was identified
- Other individual factors (i.e. attitudinal variables) play a crucial role
and age cannot be a primary predictor of performance

33. What do you think?
• Do you think the GJ test used to assess L2
morphosyntactic development appropriately
measured the performance? Other possibilities?
• Were experimental and attitudinal factors
sufficiently taken into account to demonstrate age
of arrival is the most crucial factor?

34. DeKeyser (2000)
Goal of the study:!
•To assess the effect of age on ultimate attainment in L2
morphosyntax: Replication of Johnson and Newport’s (1989)
study
•To assess the effect of verbal ability (foreign language
learning aptitude) on ultimate attainment
: Testing of Fundamental Difference Hypothesis

35. Literature review
• CPH: Decline of language learning ability does not suddenly
occur around puberty but seems to take place gradually from
ages 6 or 7 to 16 or 17 and beyond
• Fundamental Difference Hypothesis (Bley-Vroman, 1988):
- Adults can no longer rely on the innate mechanisms for
implicit language acquisition and must rely on alternative,
problem-solving mechanisms (verbal-analytic problem-solving
skills)
- Characterized by strong individual differences

36. DeKeyser’s prediction
•All late-learning achievers of near-native status must
have high verbal ability.!
•Early-learning achievers of (near-)native status will
not show any effect of verbal ability.

37. H1
Hypothesis
Participants in this study will show a strong negative!
correlation between age of arrival and performance on!
a grammaticality judgment test, but with some overlap!
in range between child and adult acquirers.!
H2
Those adult acquirers, however, who score within the!
range of child acquirers will all have high verbal!
aptitude, which may have allowed them, at least in part,!
to learn the L2 grammar through explicit reflection on!
rules.!
H3
Different elements of grammar will show different!
correlations with age of acquisition; not all structures are!
equally sensitive to the critical period effect.

38. JN (1989) DeKeyser (2000)
Method
Participants # 46 Korean Chinese 57 Hungarian
age of arrival
range
3-39
(Early:3-15; Late: 17-39)
1-40
socio-economic
status
homogeneity (college
studentfaculty
members
widely varied
occupations (blue-collar
workers ~ professionals)
length of
residence
at least 5 yrs
(av. 9.8-9.9 yrs)
at least 10 yrs
(av. 34 yrs)
Measurement GJT
GJT+Analytical verbal
ability (aptitude
test:MLAT)
item # in GJT 276 200

39. Result 1: Age of acquisition ultimate attainment
175~
• Strong negative correlation
between AA GJ test (-.63;
p.001) for the whole group !
• Overlap early/after16 yrs
learners=very small
D: r=-.63* JN: r=-.77*
16

40. Result 2: The role of aptitude
• Aptitude test: !
- Average 4.7 of 20, sd. 2.79
- 6 or above (+.46) was considered “high aptitude”
- Resulted in 15 individuals
• Aptitude scores did not correlate with:!
- Age of arrival
- GJ test score (whole group): r=.13 (ns)
- GJ test score (early learners only 16 yrs): .07 (ns)
• But did correlate significantly with:!
- GJ test score (late learners only ≥ 16): .33 (p.05)

41. Result 1: Age of acquisition Ultimate attainment
High
aptitude!
175~
• Strong negative correlation
between AA GJ test (-.63;
p.001) for the whole group !
• Overlap early/after16 yrs
learners=very small
Independent of
AP score
D: r=-.63* JN: r=-.77*
16

42. R2: Main findings
• Early learners got high test scores regardless of their aptitude!
scores; the only late learners to get high test scores had high!
aptitude scores!
!
• Years of schooling did not correlate with GJ scores!
!
• Exactly as predicted if post-CPH learners have to rely on!
more explicit learning mechanisms to learn a second!
language!

43. Result 3: Individual Structure
• High correlations with age arrival:!
- determiners omitted / used with abstract nouns
- wh-questions without do-support /subject-verb inversion
• Low correlation with age arrival: !
- word order
- yes-no questions lacking do-support
- gender errors in pronouns

44. R3: Main findings
• Different things seem to be differently affected by the age!
effects, but there are significant age-of-arrival effects on!
many of the items!
!
• Some structures, still, showed no correlation with aptitude!
everybody got them, regardless of age-of-arrival regardless!
of aptitude.!
!
• Why? DeKeyser suggests it is a function of salience.!
Ex. do-support in yes-no questions (initial), pronoun gender (corrected), basic
word order (initial, final)!
!

45. H1
Hypothesis
Participants in this study will show a strong negative!
correlation between age of arrival and performance on!
a grammaticality judgment test, but with some overlap!
in range between child and adult acquirers.!
H2
Those adult acquirers, however, who score within the!
range of child acquirers will all have high verbal!
aptitude, which may have allowed them, at least in part,!
to learn the L2 grammar through explicit reflection on!
rules.!
H3
Different elements of grammar will show different!
correlations with age of acquisition; not all structures are!
equally sensitive to the critical period effect.

46. Summing up
!
H1 !
- Strong negative correlation age of arrival GJ test score (r=.63*)!
- Overlapped scores between adult early learners (16) = very small !
!
H2 !
- Early learners got high test scores regardless of their aptitude scores!
⇔ only late learners to get high test scores had high aptitude scores!
- Post-CPH learners ( 16) are likely to rely on more explicit learning !
mechanisms!
!
H3 !
- Different structures showed different degrees of correlation with age of arrival!
- Salience of specific structures plays a role in the ease or difficulty with which!
they are acquired in an L2. !
!!

47. Conclusion implication
• Conclusion: CPH exists and constrains implicit learning!
mechanisms.!
• Adults (≥16yrs) with high cognitive maturity tend to lose!
equipment required for the implicit induction of!
the abstract patterns and better at leaning L2 explicitly !
• Policy implication: real implicit learning even by kids!
requires a lot of input (e.g., immersion and exposure time)!
• Does not warrant a policy of a few hours of language!
instruction per week in elementary schools.!

48. Birth
4
6-7
12 L1 late learners: higher rate and greater variety errors (12)
16-17
Age of arrival and maturational
constraints on L1L2
Native-like fluency (4: L1; 7:L2)
Start to decline of L1 (Newport: 6~7) !
L2 performance (8~10:JN)
After puberty: end of maturational constraints ?(JN/DK)
Age of
arrival
Losing implicit learning mechanism (6-7~16~17)
- No age effect: indivi. differences!
- High aptitude adults+ explicit learning=++L2 ability ?

49. Seems convincing, but…
• DeKeyser (2000) only examined one aspect of
aptitude, language analytical ability
• Yes, adults will be likely to rely on more conscious /
explicit learning strategies
• However…all adult leaners are good at “analytic”
type of learning??

50. What do you think?
• Is language aptitude only a factor in explicit L2
learning or is it involved in implicit/incidental
learning?
• Do adult learners exclusively rely on explicit type of
learning? Isn’t implicit type of learning effective
anymore in adult L2 acquisition or school-based
instruction?
• If so, does explicit type of learning successfully
result in native-like L2 attainment?

51. Skehan’s model of language aptitude (Skehan, 2002)
Produce
chunk rule
Memory, chunking,
retrieval process
Attention to
form
Generalizing
restructuring
the form !
Integration to
IL
Easily
accurately use
the form
Auditory
coding,
segmentation!
attention,
WM, form
sensitivity, inductive,
restructuring ability
Automatization,
proceduralization,
retrieval process

52. Two aspects of L2 processing !
(Segalowitz et.al 2011,pp.172-173 )
Easier for FonF!
(cognitive load ↓)
Reduced lexical
competition
Greater lexical
competition
Recruitment of
attentional resources while
using L2!
(cognitive load ↑）

53. Sternberg’s three types of aptitude (Sternberg, 2002)
Analytical
intelligence
the ability to analyse, compare and evaluate
Creative
intelligence
the ability to produce novel solutions to problems
Practical
intelligence
the capacity to adapt to, to shape and to select
environments suited to one’s abilities
• Aptitude tests have generally targeted “analytical” intelligence,!
but lesser “creative” “practical” intelligence, because teaching
methods have typically emphasized this !
!
• Instruction needs to be matched to the particular type of ability!
a learner is strong in!

54. Final comments
• Generally, younger learners are better equipped to engage in
implicit learning and older learners rely more on explicit learning
• High/low language aptitude cannot be easily distinguished. Different
aspects of aptitude (i.e. analytical creative) may tap both explicit
and implicit learning processes
• Matching individual aptitude types at different ages and type of
instruction may effectively facilitate both implicit and explicit learning
• In L2 classroom for adult learners, instructors must pay more
attention to how adult learners explicitly and implicitly learn by
engaging in different types of activities (controlled analytical type;
meaning-focused, open-ended type). If implicit learning mechanism
decay in adult learners, communicative tasks facilitating implicit
process of L2 will be worth implementing in classroom

55. For the future research…
• The core questions to guide current and further research
on L2 age effects are “whether there is a specific
period of decline in the ability of implicit language
learning, and whether such decline is due to
maturational factors” (DeKeyser, 2012. p.446)
• Implicit/explicit processing shift in L2 may occur in a
different developmental frame. This shift depends on the
age of learners (child vs. adult) but also the context of
learning (classroom vs. naturalistic), different aspects
of L2 (vocabulary vs. grammar, or pronunciation)
(DeKeyser, 2003)

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