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The Critical Period Hypothesis for Second Language Acquisition: Tailoring the Coat of Many Colors



The present contribution represents an extension of David Singleton’s (2005) IRAL chapter, “The Critical Period Hypothesis: A coat of many colours”. I suggest that the CPH in its application to L2 acquisition could benefit from methodological and theoretical tailoring with respect to: the shape of the function that relates age of acquisition to proficiency, the use of nativelikeness for falsification of the CPH, and the framing of predictors of L2 attainment.
The Critical Period Hypothesis for Second
Language Acquisition: Tailoring the Coat
of Many Colors
David Birdsong
Abstract The present contribution represents an extension of David Singleton’s
(2005) IRAL chapter, ‘The Critical Period Hypothesis: A coat of many colours’’.
I suggest that the CPH in its application to L2 acquisition could benefit from
methodological and theoretical tailoring with respect to: the shape of the function
that relates age of acquisition to proficiency, the use of nativelikeness for falsifi-
cation of the CPH, and the framing of predictors of L2 attainment.
1 Introduction
David Singleton’s (2005) study, ‘The Critical Period Hypothesis: A coat of many
colors’’, is the second most-cited article ever to appear in International Review of
Applied Linguistics in Language Teaching. At its core, the piece is a critique of the
Critical Period Hypothesis (CPH) as it has been applied in the context of second
language acquisition (L2A). Singleton argues that, as an account of constraints on
L2A attainment, the CPH is underspecified in the literature. Crystallizing the
sometimes vague and decidedly diverse positions advanced by researchers in the
CPH tradition, Singleton (2005: 280) writes: ‘For some reason, the language
acquiring capacity, or some aspect or aspects thereof, is operative only for a
maturational period which ends some time between perinatality and puberty’’.
With respect to the notion of ‘period’, Singleton notes that various researchers
have pegged the end of the CP for phonetics/phonology at ages ranging from one
year to puberty. As for the affected language learning capacities, Singleton’s
review of the literature reveals that CP researchers have put forth accounts of
deficits in: general language learning ability, non-innate linguistic features, innate
D. Birdsong (&)
University of Texas at Austin, Texas, USA
M. Pawlak and L. Aronin (eds.), Essential Topics in Applied Linguistics
and Multilingualism, Second Language Learning and Teaching,
DOI: 10.1007/978-3-319-01414-2_3, Springer International Publishing Switzerland 2014
linguistic features, specific subparts of innate features, and implicitly acquired
linguistic features. As concerns the underlying sources of CP effects, Singleton’s
survey tallies six accounts of a neurobiological nature, four in terms of cognitive
development, and four relating to affect and motivation.
Singleton (2005: 280) characterizes with trademark pithiness his notion of ‘the
manifoldness’ of the CPH:
My conclusion from this exploration is that the CPH cannot plausibly be regarded as a
scientific hypothesis either in the strict Popperian sense of something which can be fal-
sified (see, e.g. Popper 1959) or indeed in the rather looser logical positivist sense of
something that can be clearly confirmed or supported (see, e.g. Ayer 1959). As it stands it
is like the mythical hydra, whose multiplicity of heads and capacity to produce new heads
rendered it impossible to deal with.
From Singleton’s perspectives on the CPH/L2A, ‘‘a coat of many colors’ is indeed
an apt metaphor.
The present contribution piggybacks on Singleton’s work, taking complemen-
tary perspectives on mainstream research conducted in service of the CPH/L2A.
Adding a fitting metaphor to Singleton’s original title, I attempt to show that the
coat of many colors might warrant some methodological and theoretical tailoring to
accommodate the facts and phenomena associated with age and attainment in L2A.
2 What Critical Periods Look Like
To make a case for a CP in the L2 context, it does not suffice to demonstrate that
age of onset of L2 learning (often referred to as age of acquisition or AoA) and
ultimate L2 attainment are related. To qualify as a period, the geometry of the
function relating AoA to performance (usually characterized in terms of linguistic
proficiency or processing ability) should contain a slope that is bounded at some
points along the function.
Many studies have found AoA effects over the full span of AoA’s, suggesting
unbounded functions (Birdsong 2005). Conversely, non-linearities or inflections in
the AoA-attainment function have been interpreted as suggestive of a period, in the
sense that changes in slope would mean that AoA-related effects are bounded
(Hakuta et al. 2003; Stevens 2004). The logic here is that a significant slope
change would be consistent with a qualitative change in sensitivity of the learning
mechanism. To suggest that maturational effects are at play, the changes in slope
should line up with recognized developmental milestones that are uncontrover-
sially maturational in nature.
In this context, Birdsong and Molis (2001) reanalyzed the L2 proficiency data
from Johnson and Newport’s (1989) study of Korean and Chinese learners of L2
English. Using a piecewise linear regression model, the reanalysis placed the
breakpoint in Johnson and Newport’s AoA-proficiency slope at 18 years, i.e. at an
AoA beyond puberty. Similarly, Vanhove (2013) applied piecewise regression
44 D. Birdsong
analyses to DeKeyser et al.’s (2010) data from Russian immigrants learning L2
English in North America and L2 Hebrew in Israel. Vanhove’s reanalysis of
DeKeyser et al.’s Hebrew grammaticality judgment results revealed that including
an inflection point in the AoA-attainment function did not result in a better fit than
a simple linear regression model. In other words, AoA effects were best modeled
as a straight-line function, across the full range of AoA. The reanalysis of the
English grammaticality judgment results revealed that a model with a breakpoint
at around AoA =16 was a marginal improvement over a simple linear model.
However, like the Hebrew data, the slope of the function after AoA =16 did not
flatten, i.e. a decline in performance continued throughout adult AoA.
Vanhove’s study suggests that piecewise regression models, which have been
used only infrequently in L2 attainment studies, are appropriate for determining
whether the timing and geometry of the AoA-attainment function conform to
assumptions of what a CP should look like.
Made-to-measure analytical methods
may be required to suitably fit the coat to the function.
3 Nativelikeness and the CPH/L2A
Long (1990) stipulates that the way to falsify the CPH in the L2A context would
be to find a single late learner who is indistinguishable from an adult monolingual
native. The operational logic goes something like this: the absence of observed
nativelikeness is due to maturational factors, and nativelikeness can disconfirm the
On a complementary view of non-nativelikeness, many researchers point out that
non-monolingual-likeness in both the L1 and the L2 is a defining characteristic of
bilingualism (early and late) (for a review, see Ortega 2009: 26–27). For example,
VOT values of the L1 may extend toward those of the L2, just as VOT values of the
L2 may extend toward those of the L1 (see e.g. Fowler et al. 2008). Among bil-
inguals, effects of maturation (in the sense of biologically determined declines in
learning ability) cannot straightforwardly explain the fact that syntax, lexicon, and
phonology of the L1 are altered in bilingualism, and have features reflecting contact
with and use of the L2 (see e.g. Cook 2003). Non-monolingual-nativelikeness in the
Granena and Long (2013) applied multiple linear regression analyses to the relationship of
Chinese natives’ AoA to their attainment in L2 Spanish morphosyntax, phonology, and lexis and
collocation. For each of these three linguistic domains, including breakpoints in the model
revealed a small (5 %) but statistically significant increase in variance accounted for, as
compared to the variance accounted for in a model with no breakpoints. According to the authors,
the fact that the improvement was so small ‘could mean that the less complex (i.e. more
parsimonious) model with no breakpoints is already a good enough fit to the data or, alternatively,
that a larger sample size is needed to compensate for the loss of degrees of freedom and to
minimize the risk of overfitting’ (2013: 326–327).
The Critical Period Hypothesis for Second Language Acquisition 45
L1 of bilinguals cannot be due to maturationally induced impairment of a presumed
language learning mechanism, inasmuch as the L1 has been fully acquired, before
the end of maturation.
Arguably, the fact that the L1 can be influenced by the L2 in adulthood is
evidence for maturationally conditioned representational plasticity. In other words,
non-monolingual nativelikeness in the L1 is suggestive of a capacity to learn
language in adulthood. For example, ‘speaking with an accent in the native lan-
guage’ is common among immigrants returning to their homeland for visits, as are
noticeable changes of accent among individuals who move across dialect
boundaries within a single country. Such permeability of the L1 would not be
possible if the neural systems underlying phonetic perception and production were
not plastic. To fully clothe the big-picture facts about late L2 and late L1 learning,
the CPH/L2A coat might benefit from some broadening through the shoulders.
4 Scrutiny Across the Board
According to Long (1990) and Hyltenstam and colleagues (e.g. Hyltenstam and
Abrahamsson 2003; Abrahamsson and Hyltenstam 2009), there are two key ele-
ments of the linkage of nativelikeness to the CPH/L2A. One is the requirement that
the nativelikeness in the L2 must be observed ‘across the board’, that is, with
respect to all L2 linguistic features and processes, for it to be sufficient to falsify
the CPH. The other is that the evidence for (non)-nativelikeness (be it, presumably,
behavioral or brain-based) should be uncovered from close scientific scrutiny, lest
some evidence be overlooked. Thus, on this view, an individual who appears
nativelike to the casual observer or on coarse or too-easy performance measures is
insufficient evidence for rejecting the CPH. In sum, falsification of the CPH/L2A
would require ‘scrutinized nativelikeness’ (Abrahamsson and Hyltenstam 2009)on
a comprehensive set of linguistic measures.
There is a sensible rationale for psycholinguists to look beyond what is noticed
by the untrained ear. With sensitive measures, our understanding of linguistic
behaviors—especially inter-group and inter-individual differences—is enhanced.
In the L2 context, as in scientific inquiry generally, the precision of information
available from granular observation is valuable and welcome. From this per-
spective, there is no argument with scrutiny. The concern is with the application of
evidence for non-nativelikeness—be it obtained by scrutiny or by any other
methodological orientation—to theory. Monolingual-bilingual differences are
inevitable, and more differences are sure to emerge from challenging tasks and
fine-grained analyses than from simple tasks and coarse analyses. But it is not clear
that non-monolingual-like behaviors and brain functions are decisive for CPH/
L2A theory. Given what is known about reciprocal L1-L2 influences in bilinguals’
behaviors, evidence for non-nativelikeness—be it detected on the street or under
microscopic examination, be it present in outer patches or inner pockets, in bolts of
cloth or in buttonholes—does not compel, uniquely, a maturational explanation.
46 D. Birdsong
And so it is with across the board nativelikeness. Since bilinguals are not like
monolinguals in either of their languages, it is hard to argue that comprehensive
nativelikeness, scrutinized or not, should be held up as the gold standard for
falsifying the CPH/L2A.
If the idea is to look around for non-nativelikeness in bilingualism, then non-
nativelikeness will eventually be found. If the follow-on idea is to stipulate that
across-the-board nativelikeness is what is required to disconfirm the CPH, then the
CPH is invulnerable to falsification. This being the case, the coat would need some
letting out in the chest to accommodate the Kevlar vest underneath.
5 Framing the Issues
A study by DeKeyser (2000), entitled ‘The robustness of critical period effects in
second language acquisition’’, investigates the roles of factors such as AoA, lan-
guage learning aptitude, and years of schooling in predicting L2 English gram-
maticality judgment (GJ) accuracy by 57 Hungarian immigrants to the US. A look
at each of these factors in turn is revealing.
AoA. For all participants, AoA was predictive (r=-0.63, p\0.001). On the
other hand, breakout correlations with groups divided by early arrivals
(AoA \16; n =15; r=-0.26 ns), and late arrivals (AoA 17–40; n =42;
r=-0.04 ns), revealed no significant declines at either pre- maturational or
post-maturational AoA epochs. Thus, definitional evidence for a critical period,
in the form of pre-maturational declines in proficiency, is not found. DeKeyser
acknowledges this failure to replicate the pre-maturational AoA effects observed
by Johnson and Newport (1989) (the items used in DeKeyser’s grammaticality
judgment task were a slightly modified subset of those used by Johnson and
Newport). DeKeyser considers this discrepancy ‘‘hard to interpret’ (2000: 513),
and goes on to develop an explanation based on putative artifacts of sampling
(2000: 514).
Aptitude. DeKeyser administered to all participants a Hungarian-language
adaptation of Carroll and Sapon’s (Carroll and Sapon 1959)Modern Language
Aptitude Test. The average aptitude score of all participants was a low 4.7 out of
a possible 20. DeKeyser divided the 57 participants into a high aptitude group
(n =15) whose aptitude scores were 6 or higher, and an average- or low-
aptitude group consisting of 42 participants. To clarify, the 15- and 42-partic-
ipant breakouts for high aptitude and average/low aptitude, respectively, were
not the same participants as the groups of 15 early arrivals and 42 late arrivals.
Across all 57 participants, aptitude was not predictive of GJ scores
(r=0.13 ns). The reported correlation of aptitude with GJ scores for early
arrivals was not significant either (r=0.07 ns). However, for late arrivals, a
significant positive correlation of aptitude and GJ scores was observed
(r=0.33, p\0.05). DeKeyser had predicted that adult learners would not
The Critical Period Hypothesis for Second Language Acquisition 47
score within the range of early AoA participants unless they had high language
learning aptitude. The combination of: a significant positive correlation of
aptitude and performance among late arrivals, a non-significant correlation
of aptitude and performance for early learners, the performance near ceiling of
early learners, and an examination of 5 (of 6) higher-aptitude late learners whose
GJ scores were within the range of early learners, leads DeKeyser to the fol-
lowing generalization: ‘Whereas the younger acquirers in the present study all
reached a native or near-native level regardless of aptitude, only the adults with
above average aptitude eventually became near native’’ (2000: 515). ‘Aptitude
plays a role for adult learners’ (2000: 515) in the sense that, on L2 proficiency
measures, high aptitude trumps, or compensates for, high AoA. Thus, the
basting that sews together the AoA variable and proficiency is the interaction of
AoA and an additional learner variable, language learning aptitude: aptitude
conditions performance among late learners, but not among early learners. This
is a notable finding, to the extent that its interpretation allows for rationalization
of high GJ scores among late learners. However, what is also notable, and what
the DeKeyser study does not adequately investigate in its data, is a clear-cut set
of relationships involving the education variable.
Years of schooling. With the data provided in Appendix A of the DeKeyser
chapter, I conducted correlations of years of schooling with performance on the
grammaticality judgment task. I found that, over all AoA (n =57), years of
schooling significantly correlate with grammatical proficiency (r=0.45,
p\0.001). Education also predicts GJ scores among late learners (n =42;
r=0.51, p\0.01) as well as among early arrivals (n =15; r=0.78,
With learners separated into aptitude groups, my analysis reveals
that education is again predictive of proficiency. For the 15 high aptitude par-
ticipants, years of schooling correlate significantly with GJ scores (r=0.564,
p\0.05). Likewise, for the 42 low- to average-aptitude participants, education
predicts proficiency (r=0.43, p\0.01). Meanwhile, education and aptitude
are not correlated over all AoA (r=0.03 ns), nor among early arrivals
(r=0.006 ns), nor among late arrivals (r=0.08 ns), suggesting the indepen-
dent contributions of education and aptitude. To summarize, years of schooling
predict GJ results across all relevant correlations. Importantly, unlike AoA and
unlike aptitude, the ‘education effect’ is systematic: significant correlations are
not restricted to certain AoA spans or certain aptitude levels.
The DeKeyser (2000) narrative is about finding a connection between AoA and
L2 proficiency that is consistent with the CPH/L2A. But by framing the study
around the ‘robustness of critical period effects’, the most robustly predictive
factor in proficiency—education—is neglected (see Hakuta et al. 2003 on the role
of education in L2 proficiency over AoA).
DeKeyser (2000: 515) erroneously reports that the correlation of years of schooling and GJ
scores is r=0.006 ns, for early arrivals, and r=0.08 ns, for late arrivals. In fact, these reported
coefficients reflect correlations of years of schooling with aptitude; see discussion to follow.
48 D. Birdsong
Researchers in SLA have an interest in knowing what factors account for L2
proficiency in a sampled population. This interest is not limited to explanations of
high-aptitude late learners’ proficiency as a function of assumptions of the CPH/
L2A. A more fundamental concern is accounting for L2 proficiency globally, over
all AoA and over all aptitudes. Perhaps the coat’s palette might include a few
neutral tones alongside the many bespoke hues.
6 Conclusion
The CPH coat of many colors, pointedly so named by David Singleton, has a
history going back to Penfield and Roberts (1959) and Lenneberg (1967). Over the
ensuing years the garment has graced the torso of many a modish scholar. The
present contribution has suggested that a gusset here, a gather there, might mean
the difference between a well-worn coat and one that is worn well.
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50 D. Birdsong
... Many critical periods, with different sequences and end-points, have been proposed (Singleton and Leśniewska, 2021), for example, 18 years of age for sentence structure (Hartshorne et al., 2018;Chen and Hartshorne, 2021). Indeed the adult brain retains far greater plasticity than hitherto thought (Singleton and Leśniewska, 2021) as shown by immigrants (sequential bilinguals) often speaking with accents in their native language when returning to their homeland and individuals changing their accent when moving from one dialect area to reside in another within the same country (Birdsong, 2014). Such examples not only question the validity of younger-the-better but also suggest inherent problems in using monolingual nativelikeness as a measure of foreign language attainment (Birdsong, 2014). ...
... Indeed the adult brain retains far greater plasticity than hitherto thought (Singleton and Leśniewska, 2021) as shown by immigrants (sequential bilinguals) often speaking with accents in their native language when returning to their homeland and individuals changing their accent when moving from one dialect area to reside in another within the same country (Birdsong, 2014). Such examples not only question the validity of younger-the-better but also suggest inherent problems in using monolingual nativelikeness as a measure of foreign language attainment (Birdsong, 2014). Rather than a scientific hypothesis, Singleton (2005) likens the critical period hypothesis to the mythical hydra: impossible to deal with because of its multiple heads and ability to produce new ones. ...
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... Thirdly, critical period was considered as a gradual decline associated with age throughout the whole of a learner's life (Flege, Munro, & MacKay, 1995;Hakuta, Bialystok, & Wiley, 2003). However, as underlined by Birdsong (2013Birdsong ( , 2018, in particular, the link between age of onset of L2 learning and the ability to attain a native-like L2 proficiency is complex and the concept of any critical period hypothesis is problematic. Even if the degree attained by the speakers in L2 acquisition is "conditioned by age" of onset of learning, "which itself conditions [the brain] plasticity", age also impacts other factors such as experience in the L2 and language dominance which can be used as predictors for the variability in L2 attainment among speakers (Birdsong, 2018, p. 13-14). ...
... For the most precise evaluation of nativelikeness of an L2 speaker all linguistic aspects of the speaker's L2 should be measured and carefully analysed in detail. Consequently, the critical period hypothesis and the effect of age of onset of learning on the L2 native-likeness might be contested only if at least one late bilingual who was identical to a monolingual native speaker in every imaginable measure and knowledge of L2 was identified (Birdsong, 2013(Birdsong, , 2018. ...
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... Regarding this issue, the role of maturational constraints on L2 acquisition and processing has been a topic of considerable theoretical debate (Slabakova, 2016). One view keeps with the critical period hypothesis for L2 acquisition (Birdsong, 2014a), which posits that there exists a qualitative difference in linguistic competence between L1 speakers and adult L2 learners. Conversely, other researchers contend that L1 and L2 competence and processing mechanisms are not qualitatively distinct from each other. ...
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... Earlier research posited puberty as the time frame after which native-like achievement becomes more difficult (e.g., Johnson and Newport, 1989;DeKeyser, 2000). However, later research has shown some criticism of this position and suggested the importance of other factors, such as length of exposure or education (e.g., Hakuta et al., 2003;Birdsong, 2014). A recent study found strong statistical evidence for native-like attainment when language acquisition began before 10-12 years (Hartshorne et al., 2018). ...
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Previous research on the processing of language embedded in a rich visual context has revealed the strong effect that a recently viewed action event has on language comprehension. It has been shown that listeners are more likely to view the target object of a recently performed event than look at the target object of a plausible future event during sentence utterance, regardless of the tense cue. In the current visual-world eye-tracking experiments, we tested the strength of the recently observed visual context with a group of English monolingual and two groups of English–French early and late bilingual speakers. By comparing these different groups, we examined whether bilingual speakers, as a consequence of greater cognitive flexibility when integrating visual context and language information, show early anticipatory eye-movements toward the target object. We further asked whether early and late bilinguals show differences in their processing. The findings of the three eye-tracking experiments revealed an overall preference for the recently seen event. However, as a result of the early provision of tense cue, this preference was quickly diminished in all three groups. Moreover, the bilingual groups showed an earlier decrease in reliance on the recently seen event compared to monolingual speakers and the early bilinguals showed anticipatory eye-movements toward the plausible future event target. Furthermore, a post-experimental memory test revealed that the bilingual groups recalled the future events marginally better than the recent events, whereas the reverse was found in the monolingual groups.
... Linguistic features that are perceived by the learner to be similar in both languages can result in positive transfer, facilitating L2 acquisition (Ionin, Zubizarreta, & Maldonado, 2008;Jarvis & Odlin, 2000). Non-overlapping features can also have negative effects on learning when structures in the L1 interfere with nascent L2 knowledge (Bhela, 1999;Birdsong, 2014;MacWhinney, 2007). The way that the L1 and L2 intertwine, however, cannot be comprehensively expressed as an accumulation of independent positive and negative interactions. ...
Many languages use the same letters to represent different sounds (e.g., the letter P represents /p/ in English but /r/ in Russian). We report two experiments that examine how native language experience impacts the acquisition and processing of words with conflicting letter-to-sound mappings. Experiment 1 revealed that individual differences in nonverbal intelligence predicted word learning and that novel words with conflicting orthography-to-phonology mappings were harder to learn when their spelling was more typical of the native language than less typical (due to increased competition from the native language). Notably, Experiment 2 used eye tracking to reveal, for the first time, that hearing non-native spoken words activates native language orthography and both native and non-native letter-to-sound mappings. These findings evince high interactivity in the language system, illustrate the role of orthography in phonological learning and processing, and demonstrate that experience with written form changes the linguistic mind.
... Such a claim is made, for example, by DeKeyser (2000) in relation to those of his immigrant late learners who performed at a native level, all of whom, he reported, as showing high aptitude. Birdsong's (2014) reanalysis of the data in question, however, suggests that education was a more robust predictor of the proficiency results than aptitude. In any case, it is not clear that language aptitude is simply an innate trait (cf. ...
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This article focuses on the uncertainty surrounding the issue of the Critical Period Hypothesis. It puts forward the case that, with regard to naturalistic situations, the hypothesis has the status of both “not proven” and unfalsified. The article analyzes a number of reasons for this situation, including the effects of multi-competence, which remove any possibility that competence in more than one language can ever be identical to monolingual competence. With regard to the formal instructional setting, it points to many decades of research showing that, as critical period advocates acknowledge, in a normal schooling situation, adolescent beginners in the long run do as well as younger beginners. The article laments the profusion of definitions of what the critical period for language actually is and the generally piecemeal nature of research into this important area. In particular, it calls for a fuller integration of recent neurolinguistic perspectives into discussion of the age factor in second language acquisition research.
... While there is no doubt that delayed first language acquisition (as observable sometimes in hearing impaired children and in fortunately rare cases of feral children such as Genie, e.g. Curtiss, Fromkin, Krashen, Rigler, & Rigler, 1974) entails irreparably altered core linguistic skills, age related limitations in second language acquisition are more nuanced (Birdsong, 2014(Birdsong, , 2018. The comparison with studies on first language attrition has been particularly interesting in this respect. ...
While it has long been assumed that brain plasticity declines significantly with growing maturity, recent studies in adult subjects show grey and white matter changes due to language learning that suggest high adaptability of brain structures even within short time-scales. It is not known yet whether other language development phenomena, such as attrition, may also be linked to structural changes in the brain. In behavioral and neurocognitive research on language attrition and crosslinguistic influence, findings suggest high plasticity as language interaction patterns of bilingual speakers change constantly and from early stages of language acquisition onwards. In this paper we will speculate on possible links between brain plasticity and L1 attrition in adult bilinguals, with particular attention to a number of factors that are put forward in memory frameworks in order to explain forgetting: time elapsed, frequency of L1 use, and interference from L2. In order to better understand the time-scales involved in the plastic changes during bilingual development, we then discuss some recent studies of re-exposure to L1 in formerly attrited immigrants, and their implications with respect to brain plasticity.
... To conclude, this study provides a Poverty of Stimulus argument for adult L2 acquisition. Consequently, it presents a challenge for both usage-based approaches and certain formulations of a critical period for second language acquisition (for a modern discussion, see, for example, Birdsong, 2014) that suggest that adult learners have no access to UG. We suggest that a deeper understanding of second language acquisition requires positing a linguistic module with its own principles of development working in tandem with but independent of domain-general principles. ...
This article provides a Poverty of Stimulus argument for the participation of a dedicated linguistic module in second language acquisition. We study the second language (L2) acquisition of a subset of English infinitive complements that exhibit the following properties: (a) they present an intricate web of grammatical constraints while (b) they are highly infrequent in corpora, (c) they lack visible features that would make them salient, and (d) they are communicatively superfluous. We report on an experiment testing the knowledge of some infinitival constructions by near-native adult first language (L1) Spanish / L2 English speakers. Learners demonstrated a linguistic system that includes contrasts based on subtle restrictions in the L2, including aspect restrictions in Raising to Object. These results provide evidence that frequency and other cognitive or environmental factors are insufficient to account for the acquisition of the full spectrum of English infinitivals. This leads us to the conclusion that a domain-specific linguistic faculty is required.
This entry addresses three obvious issues that arise from any consideration of the topic of bilingualism and age. The first has to do with the relationship between maturational age and the characterization of bilingualism—the question of whether or not there is a clear empirical distinction between “early” and “late” bilingualism, relatable to a specific age; the second concerns the vexed question of whether maturational constraints—as the critical period claims—impede progress in bilinguals who begin their second language after their early years toward a very high (“native‐like”) degree of proficiency in both languages; and the third relates to the methodology of investigating maturational constraints, specifically examining the possible desirability of using the proficiency of early bilinguals rather than that of native speakers as the yardstick in the evaluation of the ultimate attainment of later L2 beginners.
While it is clear that children are more successful at learning language than adults are—whether first language or second—there is no agreement as to why. Is it due to greater neural plasticity, greater motivation, more ample opportunity for learning, superior cognitive function, lack of interference from a first language, or something else? A difficulty in teasing apart these theories is that while they make different empirical predictions, there are few unambiguous facts against which to test the theories. This is particularly true when it comes to the most basic questions about the phenomenon: When does the childhood advantage dissipate, and how rapidly does it do so? I argue that a major reason for the lack of consensus is limitations in the research methods used to date. I conclude by discussing a recently emerging methodology and by making suggestions about the path forward. Expected final online publication date for the Annual Review of Linguistics, Volume 8 is January 2022. Please see for revised estimates.
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Link to full text of Interpreting age effects in second language acquisition (Birdsong 2005) can be found at Birdsong's Google Scholar page, or at:
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In second language acquisition research, the critical period hypothesis (cph) holds that the function between learners' age and their susceptibility to second language input is non-linear. This paper revisits the indistinctness found in the literature with regard to this hypothesis's scope and predictions. Even when its scope is clearly delineated and its predictions are spelt out, however, empirical studies-with few exceptions-use analytical (statistical) tools that are irrelevant with respect to the predictions made. This paper discusses statistical fallacies common in cph research and illustrates an alternative analytical method (piecewise regression) by means of a reanalysis of two datasets from a 2010 paper purporting to have found cross-linguistic evidence in favour of the cph. This reanalysis reveals that the specific age patterns predicted by the cph are not cross-linguistically robust. Applying the principle of parsimony, it is concluded that age patterns in second language acquisition are not governed by a critical period. To conclude, this paper highlights the role of confirmation bias in the scientific enterprise and appeals to second language acquisition researchers to reanalyse their old datasets using the methods discussed in this paper. The data and R commands that were used for the reanalysis are provided as supplementary materials.
The coming of language occurs at about the same age in every healthy child throughout the world, strongly supporting the concept that genetically determined processes of maturation, rather than environmental influences, underlie capacity for speech and verbal understanding. Dr. Lenneberg points out the implications of this concept for the therapeutic and educational approach to children with hearing or speech deficits.
This book looks at changes in the first language of people who know a second language, thus seeing L2 users as people in their own right differing from the monolingual in both first and second languages. It presents theories and research that investigate the first language of second language users from a variety of perspectives including vocabulary, pragmatics, cognition, and syntax and using a variety of linguistic and psychological models. © 2003 Vivian Cook and the authors of individual chapters. All rights reserved.
A study was conducted to identify the scope and timing of maturational constraints in three linguistic domains within the same individuals, as well as the potential mediating roles of amount of second language (L2) exposure and language aptitude at different ages in different domains. Participants were 65 Chinese learners of Spanish and 12 native speaker controls. Results for three learner groups defined by age of onset (AO) – 3–6, 7–15, and 16–29 years – confirmed previous findings of windows of opportunity closing first for L2 phonology, then for lexis and collocation and, finally, in the mid-teens, for morphosyntax. All three age functions exhibited the discontinuities in the rate of decline with increasing AO associated with sensitive periods. Significant correlations were found between language aptitude, measured using the LLAMA test (Meara, 2005), and pronunciation scores, and between language aptitude and lexis and collocation scores, in the AO 16–29 group.