Click through the PLOS taxonomy to find articles in your field.
For more information about PLOS Subject Areas, click here .
Loading metrics
Open Access
Peer-reviewed
Research Article
![](http://ortec.site/777/templates/cheerup1/res/banner1.gif)
The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis
* E-mail: [email protected]
Affiliation Department of Multilingualism, University of Fribourg, Fribourg, Switzerland
- Jan Vanhove
![critical period hypothesis in language development PLOS](https://journals.plos.org/resource/img/logo-plos.png)
- Published: July 25, 2013
- https://doi.org/10.1371/journal.pone.0069172
- Reader Comments
17 Jul 2014: The PLOS ONE Staff (2014) Correction: The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis. PLOS ONE 9(7): e102922. https://doi.org/10.1371/journal.pone.0102922 View correction
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.
Citation: Vanhove J (2013) The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis. PLoS ONE 8(7): e69172. https://doi.org/10.1371/journal.pone.0069172
Editor: Stephanie Ann White, UCLA, United States of America
Received: May 7, 2013; Accepted: June 7, 2013; Published: July 25, 2013
Copyright: © 2013 Jan Vanhove. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: No current external funding sources for this study.
Competing interests: The author has declared that no competing interests exist.
Introduction
In the long term and in immersion contexts, second-language (L2) learners starting acquisition early in life – and staying exposed to input and thus learning over several years or decades – undisputedly tend to outperform later learners. Apart from being misinterpreted as an argument in favour of early foreign language instruction, which takes place in wholly different circumstances, this general age effect is also sometimes taken as evidence for a so-called ‘critical period’ ( cp ) for second-language acquisition ( sla ). Derived from biology, the cp concept was famously introduced into the field of language acquisition by Penfield and Roberts in 1959 [1] and was refined by Lenneberg eight years later [2] . Lenneberg argued that language acquisition needed to take place between age two and puberty – a period which he believed to coincide with the lateralisation process of the brain. (More recent neurological research suggests that different time frames exist for the lateralisation process of different language functions. Most, however, close before puberty [3] .) However, Lenneberg mostly drew on findings pertaining to first language development in deaf children, feral children or children with serious cognitive impairments in order to back up his claims. For him, the critical period concept was concerned with the implicit “automatic acquisition” [2, p. 176] in immersion contexts and does not preclude the possibility of learning a foreign language after puberty, albeit with much conscious effort and typically less success.
sla research adopted the critical period hypothesis ( cph ) and applied it to second and foreign language learning, resulting in a host of studies. In its most general version, the cph for sla states that the ‘susceptibility’ or ‘sensitivity’ to language input varies as a function of age, with adult L2 learners being less susceptible to input than child L2 learners. Importantly, the age–susceptibility function is hypothesised to be non-linear. Moving beyond this general version, we find that the cph is conceptualised in a multitude of ways [4] . This state of affairs requires scholars to make explicit their theoretical stance and assumptions [5] , but has the obvious downside that critical findings risk being mitigated as posing a problem to only one aspect of one particular conceptualisation of the cph , whereas other conceptualisations remain unscathed. This overall vagueness concerns two areas in particular, viz. the delineation of the cph 's scope and the formulation of testable predictions. Delineating the scope and formulating falsifiable predictions are, needless to say, fundamental stages in the scientific evaluation of any hypothesis or theory, but the lack of scholarly consensus on these points seems to be particularly pronounced in the case of the cph . This article therefore first presents a brief overview of differing views on these two stages. Then, once the scope of their cph version has been duly identified and empirical data have been collected using solid methods, it is essential that researchers analyse the data patterns soundly in order to assess the predictions made and that they draw justifiable conclusions from the results. As I will argue in great detail, however, the statistical analysis of data patterns as well as their interpretation in cph research – and this includes both critical and supportive studies and overviews – leaves a great deal to be desired. Reanalysing data from a recent cph -supportive study, I illustrate some common statistical fallacies in cph research and demonstrate how one particular cph prediction can be evaluated.
Delineating the scope of the critical period hypothesis
First, the age span for a putative critical period for language acquisition has been delimited in different ways in the literature [4] . Lenneberg's critical period stretched from two years of age to puberty (which he posits at about 14 years of age) [2] , whereas other scholars have drawn the cutoff point at 12, 15, 16 or 18 years of age [6] . Unlike Lenneberg, most researchers today do not define a starting age for the critical period for language learning. Some, however, consider the possibility of the critical period (or a critical period for a specific language area, e.g. phonology) ending much earlier than puberty (e.g. age 9 years [1] , or as early as 12 months in the case of phonology [7] ).
Second, some vagueness remains as to the setting that is relevant to the cph . Does the critical period constrain implicit learning processes only, i.e. only the untutored language acquisition in immersion contexts or does it also apply to (at least partly) instructed learning? Most researchers agree on the former [8] , but much research has included subjects who have had at least some instruction in the L2.
Third, there is no consensus on what the scope of the cp is as far as the areas of language that are concerned. Most researchers agree that a cp is most likely to constrain the acquisition of pronunciation and grammar and, consequently, these are the areas primarily looked into in studies on the cph [9] . Some researchers have also tried to define distinguishable cp s for the different language areas of phonetics, morphology and syntax and even for lexis (see [10] for an overview).
Fourth and last, research into the cph has focused on ‘ultimate attainment’ ( ua ) or the ‘final’ state of L2 proficiency rather than on the rate of learning. From research into the rate of acquisition (e.g. [11] – [13] ), it has become clear that the cph cannot hold for the rate variable. In fact, it has been observed that adult learners proceed faster than child learners at the beginning stages of L2 acquisition. Though theoretical reasons for excluding the rate can be posited (the initial faster rate of learning in adults may be the result of more conscious cognitive strategies rather than to less conscious implicit learning, for instance), rate of learning might from a different perspective also be considered an indicator of ‘susceptibility’ or ‘sensitivity’ to language input. Nevertheless, contemporary sla scholars generally seem to concur that ua and not rate of learning is the dependent variable of primary interest in cph research. These and further scope delineation problems relevant to cph research are discussed in more detail by, among others, Birdsong [9] , DeKeyser and Larson-Hall [14] , Long [10] and Muñoz and Singleton [6] .
Formulating testable hypotheses
Once the relevant cph 's scope has satisfactorily been identified, clear and testable predictions need to be drawn from it. At this stage, the lack of consensus on what the consequences or the actual observable outcome of a cp would have to look like becomes evident. As touched upon earlier, cph research is interested in the end state or ‘ultimate attainment’ ( ua ) in L2 acquisition because this “determines the upper limits of L2 attainment” [9, p. 10]. The range of possible ultimate attainment states thus helps researchers to explore the potential maximum outcome of L2 proficiency before and after the putative critical period.
One strong prediction made by some cph exponents holds that post- cp learners cannot reach native-like L2 competences. Identifying a single native-like post- cp L2 learner would then suffice to falsify all cph s making this prediction. Assessing this prediction is difficult, however, since it is not clear what exactly constitutes sufficient nativelikeness, as illustrated by the discussion on the actual nativelikeness of highly accomplished L2 speakers [15] , [16] . Indeed, there exists a real danger that, in a quest to vindicate the cph , scholars set the bar for L2 learners to match monolinguals increasingly higher – up to Swiftian extremes. Furthermore, the usefulness of comparing the linguistic performance in mono- and bilinguals has been called into question [6] , [17] , [18] . Put simply, the linguistic repertoires of mono- and bilinguals differ by definition and differences in the behavioural outcome will necessarily be found, if only one digs deep enough.
A second strong prediction made by cph proponents is that the function linking age of acquisition and ultimate attainment will not be linear throughout the whole lifespan. Before discussing how this function would have to look like in order for it to constitute cph -consistent evidence, I point out that the ultimate attainment variable can essentially be considered a cumulative measure dependent on the actual variable of interest in cph research, i.e. susceptibility to language input, as well as on such other factors like duration and intensity of learning (within and outside a putative cp ) and possibly a number of other influencing factors. To elaborate, the behavioural outcome, i.e. ultimate attainment, can be assumed to be integrative to the susceptibility function, as Newport [19] correctly points out. Other things being equal, ultimate attainment will therefore decrease as susceptibility decreases. However, decreasing ultimate attainment levels in and by themselves represent no compelling evidence in favour of a cph . The form of the integrative curve must therefore be predicted clearly from the susceptibility function. Additionally, the age of acquisition–ultimate attainment function can take just about any form when other things are not equal, e.g. duration of learning (Does learning last up until time of testing or only for a more or less constant number of years or is it dependent on age itself?) or intensity of learning (Do learners always learn at their maximum susceptibility level or does this intensity vary as a function of age, duration, present attainment and motivation?). The integral of the susceptibility function could therefore be of virtually unlimited complexity and its parameters could be adjusted to fit any age of acquisition–ultimate attainment pattern. It seems therefore astonishing that the distinction between level of sensitivity to language input and level of ultimate attainment is rarely made in the literature. Implicitly or explicitly [20] , the two are more or less equated and the same mathematical functions are expected to describe the two variables if observed across a range of starting ages of acquisition.
But even when the susceptibility and ultimate attainment variables are equated, there remains controversy as to what function linking age of onset of acquisition and ultimate attainment would actually constitute evidence for a critical period. Most scholars agree that not any kind of age effect constitutes such evidence. More specifically, the age of acquisition–ultimate attainment function would need to be different before and after the end of the cp [9] . According to Birdsong [9] , three basic possible patterns proposed in the literature meet this condition. These patterns are presented in Figure 1 . The first pattern describes a steep decline of the age of onset of acquisition ( aoa )–ultimate attainment ( ua ) function up to the end of the cp and a practically non-existent age effect thereafter. Pattern 2 is an “unconventional, although often implicitly invoked” [9, p. 17] notion of the cp function which contains a period of peak attainment (or performance at ceiling), i.e. performance does not vary as a function of age, which is often referred to as a ‘window of opportunity’. This time span is followed by an unbounded decline in ua depending on aoa . Pattern 3 includes characteristics of patterns 1 and 2. At the beginning of the aoa range, performance is at ceiling. The next segment is a downward slope in the age function which ends when performance reaches its floor. Birdsong points out that all of these patterns have been reported in the literature. On closer inspection, however, he concludes that the most convincing function describing these age effects is a simple linear one. Hakuta et al. [21] sketch further theoretically possible predictions of the cph in which the mean performance drops drastically and/or the slope of the aoa – ua proficiency function changes at a certain point.
- PPT PowerPoint slide
- PNG larger image
- TIFF original image
The graphs are based on based on Figure 2 in [9] .
https://doi.org/10.1371/journal.pone.0069172.g001
Although several patterns have been proposed in the literature, it bears pointing out that the most common explicit prediction corresponds to Birdsong's first pattern, as exemplified by the following crystal-clear statement by DeKeyser, one of the foremost cph proponents:
[A] strong negative correlation between age of acquisition and ultimate attainment throughout the lifespan (or even from birth through middle age), the only age effect documented in many earlier studies, is not evidence for a critical period…[T]he critical period concept implies a break in the AoA–proficiency function, i.e., an age (somewhat variable from individual to individual, of course, and therefore an age range in the aggregate) after which the decline of success rate in one or more areas of language is much less pronounced and/or clearly due to different reasons. [22, p. 445].
DeKeyser and before him among others Johnson and Newport [23] thus conceptualise only one possible pattern which would speak in favour of a critical period: a clear negative age effect before the end of the critical period and a much weaker (if any) negative correlation between age and ultimate attainment after it. This ‘flattened slope’ prediction has the virtue of being much more tangible than the ‘potential nativelikeness’ prediction: Testing it does not necessarily require comparing the L2-learners to a native control group and thus effectively comparing apples and oranges. Rather, L2-learners with different aoa s can be compared amongst themselves without the need to categorise them by means of a native-speaker yardstick, the validity of which is inevitably going to be controversial [15] . In what follows, I will concern myself solely with the ‘flattened slope’ prediction, arguing that, despite its clarity of formulation, cph research has generally used analytical methods that are irrelevant for the purposes of actually testing it.
Inferring non-linearities in critical period research: An overview
Group mean or proportion comparisons.
[T]he main differences can be found between the native group and all other groups – including the earliest learner group – and between the adolescence group and all other groups. However, neither the difference between the two childhood groups nor the one between the two adulthood groups reached significance, which indicates that the major changes in eventual perceived nativelikeness of L2 learners can be associated with adolescence. [15, p. 270].
Similar group comparisons aimed at investigating the effect of aoa on ua have been carried out by both cph advocates and sceptics (among whom Bialystok and Miller [25, pp. 136–139], Birdsong and Molis [26, p. 240], Flege [27, pp. 120–121], Flege et al. [28, pp. 85–86], Johnson [29, p. 229], Johnson and Newport [23, p. 78], McDonald [30, pp. 408–410] and Patowski [31, pp. 456–458]). To be clear, not all of these authors drew direct conclusions about the aoa – ua function on the basis of these groups comparisons, but their group comparisons have been cited as indicative of a cph -consistent non-continuous age effect, as exemplified by the following quote by DeKeyser [22] :
Where group comparisons are made, younger learners always do significantly better than the older learners. The behavioral evidence, then, suggests a non-continuous age effect with a “bend” in the AoA–proficiency function somewhere between ages 12 and 16. [22, p. 448].
The first problem with group comparisons like these and drawing inferences on the basis thereof is that they require that a continuous variable, aoa , be split up into discrete bins. More often than not, the boundaries between these bins are drawn in an arbitrary fashion, but what is more troublesome is the loss of information and statistical power that such discretisation entails (see [32] for the extreme case of dichotomisation). If we want to find out more about the relationship between aoa and ua , why throw away most of the aoa information and effectively reduce the ua data to group means and the variance in those groups?
Comparison of correlation coefficients.
Correlation-based inferences about slope discontinuities have similarly explicitly been made by cph advocates and skeptics alike, e.g. Bialystok and Miller [25, pp. 136 and 140], DeKeyser and colleagues [22] , [44] and Flege et al. [45, pp. 166 and 169]. Others did not explicitly infer the presence or absence of slope differences from the subset correlations they computed (among others Birdsong and Molis [26] , DeKeyser [8] , Flege et al. [28] and Johnson [29] ), but their studies nevertheless featured in overviews discussing discontinuities [14] , [22] . Indeed, the most recent overview draws a strong conclusion about the validity of the cph 's ‘flattened slope’ prediction on the basis of these subset correlations:
In those studies where the two groups are described separately, the correlation is much higher for the younger than for the older group, except in Birdsong and Molis (2001) [ = [26] , JV], where there was a ceiling effect for the younger group. This global picture from more than a dozen studies provides support for the non-continuity of the decline in the AoA–proficiency function, which all researchers agree is a hallmark of a critical period phenomenon. [22, p. 448].
In Johnson and Newport's specific case [23] , their correlation-based inference that ua levels off after puberty happened to be largely correct: the gjt scores are more or less randomly distributed around a near-horizontal trend line [26] . Ultimately, however, it rests on the fallacy of confusing correlation coefficients with slopes, which seriously calls into question conclusions such as DeKeyser's (cf. the quote above).
https://doi.org/10.1371/journal.pone.0069172.g002
Lower correlation coefficients in older aoa groups may therefore be largely due to differences in ua variance, which have been reported in several studies [23] , [26] , [28] , [29] (see [46] for additional references). Greater variability in ua with increasing age is likely due to factors other than age proper [47] , such as the concomitant greater variability in exposure to literacy, degree of education, motivation and opportunity for language use, and by itself represents evidence neither in favour of nor against the cph .
Regression approaches.
Having demonstrated that neither group mean or proportion comparisons nor correlation coefficient comparisons can directly address the ‘flattened slope’ prediction, I now turn to the studies in which regression models were computed with aoa as a predictor variable and ua as the outcome variable. Once again, this category of studies is not mutually exclusive with the two categories discussed above.
In a large-scale study using self-reports and approximate aoa s derived from a sample of the 1990 U.S. Census, Stevens found that the probability with which immigrants from various countries stated that they spoke English ‘very well’ decreased curvilinearly as a function of aoa [48] . She noted that this development is similar to the pattern found by Johnson and Newport [23] but that it contains no indication of an “abruptly defined ‘critical’ or sensitive period in L2 learning” [48, p. 569]. However, she modelled the self-ratings using an ordinal logistic regression model in which the aoa variable was logarithmically transformed. Technically, this is perfectly fine, but one should be careful not to read too much into the non-linear curves found. In logistic models, the outcome variable itself is modelled linearly as a function of the predictor variables and is expressed in log-odds. In order to compute the corresponding probabilities, these log-odds are transformed using the logistic function. Consequently, even if the model is specified linearly, the predicted probabilities will not lie on a perfectly straight line when plotted as a function of any one continuous predictor variable. Similarly, when the predictor variable is first logarithmically transformed and then used to linearly predict an outcome variable, the function linking the predicted outcome variables and the untransformed predictor variable is necessarily non-linear. Thus, non-linearities follow naturally from Stevens's model specifications. Moreover, cph -consistent discontinuities in the aoa – ua function cannot be found using her model specifications as they did not contain any parameters allowing for this.
Using data similar to Stevens's, Bialystok and Hakuta found that the link between the self-rated English competences of Chinese- and Spanish-speaking immigrants and their aoa could be described by a straight line [49] . In contrast to Stevens, Bialystok and Hakuta used a regression-based method allowing for changes in the function's slope, viz. locally weighted scatterplot smoothing ( lowess ). Informally, lowess is a non-parametrical method that relies on an algorithm that fits the dependent variable for small parts of the range of the independent variable whilst guaranteeing that the overall curve does not contain sudden jumps (for technical details, see [50] ). Hakuta et al. used an even larger sample from the same 1990 U.S. Census data on Chinese- and Spanish-speaking immigrants (2.3 million observations) [21] . Fitting lowess curves, no discontinuities in the aoa – ua slope could be detected. Moreover, the authors found that piecewise linear regression models, i.e. regression models containing a parameter that allows a sudden drop in the curve or a change of its slope, did not provide a better fit to the data than did an ordinary regression model without such a parameter.
To sum up, I have argued at length that regression approaches are superior to group mean and correlation coefficient comparisons for the purposes of testing the ‘flattened slope’ prediction. Acknowledging the reservations vis-à-vis self-estimated ua s, we still find that while the relationship between aoa and ua is not necessarily perfectly linear in the studies discussed, the data do not lend unequivocal support to this prediction. In the following section, I will reanalyse data from a recent empirical paper on the cph by DeKeyser et al. [44] . The first goal of this reanalysis is to further illustrate some of the statistical fallacies encountered in cph studies. Second, by making the computer code available I hope to demonstrate how the relevant regression models, viz. piecewise regression models, can be fitted and how the aoa representing the optimal breakpoint can be identified. Lastly, the findings of this reanalysis will contribute to our understanding of how aoa affects ua as measured using a gjt .
Summary of DeKeyser et al. (2010)
I chose to reanalyse a recent empirical paper on the cph by DeKeyser et al. [44] (henceforth DK et al.). This paper lends itself well to a reanalysis since it exhibits two highly commendable qualities: the authors spell out their hypotheses lucidly and provide detailed numerical and graphical data descriptions. Moreover, the paper's lead author is very clear on what constitutes a necessary condition for accepting the cph : a non-linearity in the age of onset of acquisition ( aoa )–ultimate attainment ( ua ) function, with ua declining less strongly as a function of aoa in older, post- cp arrivals compared to younger arrivals [14] , [22] . Lastly, it claims to have found cross-linguistic evidence from two parallel studies backing the cph and should therefore be an unsuspected source to cph proponents.
The authors set out to test the following hypotheses:
- Hypothesis 1: For both the L2 English and the L2 Hebrew group, the slope of the age of arrival–ultimate attainment function will not be linear throughout the lifespan, but will instead show a marked flattening between adolescence and adulthood.
- Hypothesis 2: The relationship between aptitude and ultimate attainment will differ markedly for the young and older arrivals, with significance only for the latter. (DK et al., p. 417)
Both hypotheses were purportedly confirmed, which in the authors' view provides evidence in favour of cph . The problem with this conclusion, however, is that it is based on a comparison of correlation coefficients. As I have argued above, correlation coefficients are not to be confused with regression coefficients and cannot be used to directly address research hypotheses concerning slopes, such as Hypothesis 1. In what follows, I will reanalyse the relationship between DK et al.'s aoa and gjt data in order to address Hypothesis 1. Additionally, I will lay bare a problem with the way in which Hypothesis 2 was addressed. The extracted data and the computer code used for the reanalysis are provided as supplementary materials, allowing anyone interested to scrutinise and easily reproduce my whole analysis and carry out their own computations (see ‘supporting information’).
Data extraction
In order to verify whether we did in fact extract the data points to a satisfactory degree of accuracy, I computed summary statistics for the extracted aoa and gjt data and checked these against the descriptive statistics provided by DK et al. (pp. 421 and 427). These summary statistics for the extracted data are presented in Table 1 . In addition, I computed the correlation coefficients for the aoa – gjt relationship for the whole aoa range and for aoa -defined subgroups and checked these coefficients against those reported by DK et al. (pp. 423 and 428). The correlation coefficients computed using the extracted data are presented in Table 2 . Both checks strongly suggest the extracted data to be virtually identical to the original data, and Dr DeKeyser confirmed this to be the case in response to an earlier draft of the present paper (personal communication, 6 May 2013).
https://doi.org/10.1371/journal.pone.0069172.t001
https://doi.org/10.1371/journal.pone.0069172.t002
Results and Discussion
Modelling the link between age of onset of acquisition and ultimate attainment.
I first replotted the aoa and gjt data we extracted from DK et al.'s scatterplots and added non-parametric scatterplot smoothers in order to investigate whether any changes in slope in the aoa – gjt function could be revealed, as per Hypothesis 1. Figures 3 and 4 show this not to be the case. Indeed, simple linear regression models that model gjt as a function of aoa provide decent fits for both the North America and the Israel data, explaining 65% and 63% of the variance in gjt scores, respectively. The parameters of these models are given in Table 3 .
The trend line is a non-parametric scatterplot smoother. The scatterplot itself is a near-perfect replication of DK et al.'s Fig. 1.
https://doi.org/10.1371/journal.pone.0069172.g003
The trend line is a non-parametric scatterplot smoother. The scatterplot itself is a near-perfect replication of DK et al.'s Fig. 5.
https://doi.org/10.1371/journal.pone.0069172.g004
https://doi.org/10.1371/journal.pone.0069172.t003
To ensure that both segments are joined at the breakpoint, the predictor variable is first centred at the breakpoint value, i.e. the breakpoint value is subtracted from the original predictor variable values. For a blow-by-blow account of how such models can be fitted in r , I refer to an example analysis by Baayen [55, pp. 214–222].
Solid: regression with breakpoint at aoa 18 (dashed lines represent its 95% confidence interval); dot-dash: regression without breakpoint.
https://doi.org/10.1371/journal.pone.0069172.g005
Solid: regression with breakpoint at aoa 18 (dashed lines represent its 95% confidence interval); dot-dash (hardly visible due to near-complete overlap): regression without breakpoint.
https://doi.org/10.1371/journal.pone.0069172.g006
https://doi.org/10.1371/journal.pone.0069172.t004
https://doi.org/10.1371/journal.pone.0069172.g007
Solid: regression with breakpoint at aoa 16 (dashed lines represent its 95% confidence interval); dot-dash: regression without breakpoint.
https://doi.org/10.1371/journal.pone.0069172.g008
Solid: regression with breakpoint at aoa 6 (dashed lines represent its 95% confidence interval); dot-dash (hardly visible due to near-complete overlap): regression without breakpoint.
https://doi.org/10.1371/journal.pone.0069172.g009
https://doi.org/10.1371/journal.pone.0069172.t005
https://doi.org/10.1371/journal.pone.0069172.t006
https://doi.org/10.1371/journal.pone.0069172.t007
https://doi.org/10.1371/journal.pone.0069172.t008
In sum, a regression model that allows for changes in the slope of the the aoa – gjt function to account for putative critical period effects provides a somewhat better fit to the North American data than does an everyday simple regression model. The improvement in model fit is marginal, however, and including a breakpoint does not result in any detectable improvement of model fit to the Israel data whatsoever. Breakpoint models therefore fail to provide solid cross-linguistic support in favour of critical period effects: across both data sets, gjt can satisfactorily be modelled as a linear function of aoa .
On partialling out ‘age at testing’
As I have argued above, correlation coefficients cannot be used to test hypotheses about slopes. When the correct procedure is carried out on DK et al.'s data, no cross-linguistically robust evidence for changes in the aoa – gjt function was found. In addition to comparing the zero-order correlations between aoa and gjt , however, DK et al. computed partial correlations in which the variance in aoa associated with the participants' age at testing ( aat ; a potentially confounding variable) was filtered out. They found that these partial correlations between aoa and gjt , which are given in Table 9 , differed between age groups in that they are stronger for younger than for older participants. This, DK et al. argue, constitutes additional evidence in favour of the cph . At this point, I can no longer provide my own analysis of DK et al.'s data seeing as the pertinent data points were not plotted. Nevertheless, the detailed descriptions by DK et al. strongly suggest that the use of these partial correlations is highly problematic. Most importantly, and to reiterate, correlations (whether zero-order or partial ones) are actually of no use when testing hypotheses concerning slopes. Still, one may wonder why the partial correlations differ across age groups. My surmise is that these differences are at least partly the by-product of an imbalance in the sampling procedure.
https://doi.org/10.1371/journal.pone.0069172.t009
The upshot of this brief discussion is that the partial correlation differences reported by DK et al. are at least partly the result of an imbalance in the sampling procedure: aoa and aat were simply less intimately tied for the young arrivals in the North America study than for the older arrivals with L2 English or for all of the L2 Hebrew participants. In an ideal world, we would like to fix aat or ascertain that it at most only weakly correlates with aoa . This, however, would result in a strong correlation between aoa and another potential confound variable, length of residence in the L2 environment, bringing us back to square one. Allowing for only moderate correlations between aoa and aat might improve our predicament somewhat, but even in that case, we should tread lightly when making inferences on the basis of statistical control procedures [61] .
On estimating the role of aptitude
Having shown that Hypothesis 1 could not be confirmed, I now turn to Hypothesis 2, which predicts a differential role of aptitude for ua in sla in different aoa groups. More specifically, it states that the correlation between aptitude and gjt performance will be significant only for older arrivals. The correlation coefficients of the relationship between aptitude and gjt are presented in Table 10 .
https://doi.org/10.1371/journal.pone.0069172.t010
The problem with both the wording of Hypothesis 2 and the way in which it is addressed is the following: it is assumed that a variable has a reliably different effect in different groups when the effect reaches significance in one group but not in the other. This logic is fairly widespread within several scientific disciplines (see e.g. [62] for a discussion). Nonetheless, it is demonstrably fallacious [63] . Here we will illustrate the fallacy for the specific case of comparing two correlation coefficients.
Apart from not being replicated in the North America study, does this difference actually show anything? I contend that it does not: what is of interest are not so much the correlation coefficients, but rather the interactions between aoa and aptitude in models predicting gjt . These interactions could be investigated by fitting a multiple regression model in which the postulated cp breakpoint governs the slope of both aoa and aptitude. If such a model provided a substantially better fit to the data than a model without a breakpoint for the aptitude slope and if the aptitude slope changes in the expected direction (i.e. a steeper slope for post- cp than for younger arrivals) for different L1–L2 pairings, only then would this particular prediction of the cph be borne out.
Using data extracted from a paper reporting on two recent studies that purport to provide evidence in favour of the cph and that, according to its authors, represent a major improvement over earlier studies (DK et al., p. 417), it was found that neither of its two hypotheses were actually confirmed when using the proper statistical tools. As a matter of fact, the gjt scores continue to decline at essentially the same rate even beyond the end of the putative critical period. According to the paper's lead author, such a finding represents a serious problem to his conceptualisation of the cph [14] ). Moreover, although modelling a breakpoint representing the end of a cp at aoa 16 may improve the statistical model slightly in study on learners of English in North America, the study on learners of Hebrew in Israel fails to confirm this finding. In fact, even if we were to accept the optimal breakpoint computed for the Israel study, it lies at aoa 6 and is associated with a different geometrical pattern.
Diverging age trends in parallel studies with participants with different L2s have similarly been reported by Birdsong and Molis [26] and are at odds with an L2-independent cph . One parsimonious explanation of such conflicting age trends may be that the overall, cross-linguistic age trend is in fact linear, but that fluctuations in the data (due to factors unaccounted for or randomness) may sometimes give rise to a ‘stretched L’-shaped pattern ( Figure 1, left panel ) and sometimes to a ‘stretched 7’-shaped pattern ( Figure 1 , middle panel; see also [66] for a similar comment).
Importantly, the criticism that DeKeyser and Larsson-Hall levy against two studies reporting findings similar to the present [48] , [49] , viz. that the data consisted of self-ratings of questionable validity [14] , does not apply to the present data set. In addition, DK et al. did not exclude any outliers from their analyses, so I assume that DeKeyser and Larsson-Hall's criticism [14] of Birdsong and Molis's study [26] , i.e. that the findings were due to the influence of outliers, is not applicable to the present data either. For good measure, however, I refitted the regression models with and without breakpoints after excluding one potentially problematic data point per model. The following data points had absolute standardised residuals larger than 2.5 in the original models without breakpoints as well as in those with breakpoints: the participant with aoa 17 and a gjt score of 125 in the North America study and the participant with aoa 12 and a gjt score of 117 in the Israel study. The resultant models were virtually identical to the original models (see Script S1 ). Furthermore, the aoa variable was sufficiently fine-grained and the aoa – gjt curve was not ‘presmoothed’ by the prior aggregation of gjt across parts of the aoa range (see [51] for such a criticism of another study). Lastly, seven of the nine “problems with supposed counter-evidence” to the cph discussed by Long [5] do not apply either, viz. (1) “[c]onfusion of rate and ultimate attainment”, (2) “[i]nappropriate choice of subjects”, (3) “[m]easurement of AO”, (4) “[l]eading instructions to raters”, (6) “[u]se of markedly non-native samples making near-native samples more likely to sound native to raters”, (7) “[u]nreliable or invalid measures”, and (8) “[i]nappropriate L1–L2 pairings”. Problem No. 5 (“Assessments based on limited samples and/or “language-like” behavior”) may be apropos given that only gjt data were used, leaving open the theoretical possibility that other measures might have yielded a different outcome. Finally, problem No. 9 (“Faulty interpretation of statistical patterns”) is, of course, precisely what I have turned the spotlights on.
Conclusions
The critical period hypothesis remains a hotly contested issue in the psycholinguistics of second-language acquisition. Discussions about the impact of empirical findings on the tenability of the cph generally revolve around the reliability of the data gathered (e.g. [5] , [14] , [22] , [52] , [67] , [68] ) and such methodological critiques are of course highly desirable. Furthermore, the debate often centres on the question of exactly what version of the cph is being vindicated or debunked. These versions differ mainly in terms of its scope, specifically with regard to the relevant age span, setting and language area, and the testable predictions they make. But even when the cph 's scope is clearly demarcated and its main prediction is spelt out lucidly, the issue remains to what extent the empirical findings can actually be marshalled in support of the relevant cph version. As I have shown in this paper, empirical data have often been taken to support cph versions predicting that the relationship between age of acquisition and ultimate attainment is not strictly linear, even though the statistical tools most commonly used (notably group mean and correlation coefficient comparisons) were, crudely put, irrelevant to this prediction. Methods that are arguably valid, e.g. piecewise regression and scatterplot smoothing, have been used in some studies [21] , [26] , [49] , but these studies have been criticised on other grounds. To my knowledge, such methods have never been used by scholars who explicitly subscribe to the cph .
I suspect that what may be going on is a form of ‘confirmation bias’ [69] , a cognitive bias at play in diverse branches of human knowledge seeking: Findings judged to be consistent with one's own hypothesis are hardly questioned, whereas findings inconsistent with one's own hypothesis are scrutinised much more strongly and criticised on all sorts of points [70] – [73] . My reanalysis of DK et al.'s recent paper may be a case in point. cph exponents used correlation coefficients to address their prediction about the slope of a function, as had been done in a host of earlier studies. Finding a result that squared with their expectations, they did not question the technical validity of their results, or at least they did not report this. (In fact, my reanalysis is actually a case in point in two respects: for an earlier draft of this paper, I had computed the optimal position of the breakpoints incorrectly, resulting in an insignificant improvement of model fit for the North American data rather than a borderline significant one. Finding a result that squared with my expectations, I did not question the technical validity of my results – until this error was kindly pointed out to me by Martijn Wieling (University of Tübingen).) That said, I am keen to point out that the statistical analyses in this particular paper, though suboptimal, are, as far as I could gather, reported correctly, i.e. the confirmation bias does not seem to have resulted in the blatant misreportings found elsewhere (see [74] for empirical evidence and discussion). An additional point to these authors' credit is that, apart from explicitly identifying their cph version's scope and making crystal-clear predictions, they present data descriptions that actually permit quantitative reassessments and have a history of doing so (e.g. the appendix in [8] ). This leads me to believe that they analysed their data all in good conscience and to hope that they, too, will conclude that their own data do not, in fact, support their hypothesis.
I end this paper on an upbeat note. Even though I have argued that the analytical tools employed in cph research generally leave much to be desired, the original data are, so I hope, still available. This provides researchers, cph supporters and sceptics alike, with an exciting opportunity to reanalyse their data sets using the tools outlined in the present paper and publish their findings at minimal cost of time and resources (for instance, as a comment to this paper). I would therefore encourage scholars to engage their old data sets and to communicate their analyses openly, e.g. by voluntarily publishing their data and computer code alongside their articles or comments. Ideally, cph supporters and sceptics would join forces to agree on a protocol for a high-powered study in order to provide a truly convincing answer to a core issue in sla .
Supporting Information
Dataset s1..
aoa and gjt data extracted from DeKeyser et al.'s North America study.
https://doi.org/10.1371/journal.pone.0069172.s001
Dataset S2.
aoa and gjt data extracted from DeKeyser et al.'s Israel study.
https://doi.org/10.1371/journal.pone.0069172.s002
Script with annotated R code used for the reanalysis. All add-on packages used can be installed from within R.
https://doi.org/10.1371/journal.pone.0069172.s003
Acknowledgments
I would like to thank Irmtraud Kaiser (University of Fribourg) for helping me to get an overview of the literature on the critical period hypothesis in second language acquisition. Thanks are also due to Martijn Wieling (currently University of Tübingen) for pointing out an error in the R code accompanying an earlier draft of this paper.
Author Contributions
Analyzed the data: JV. Wrote the paper: JV.
- 1. Penfield W, Roberts L (1959) Speech and brain mechanisms. Princeton: Princeton University Press.
- 2. Lenneberg EH (1967) Biological foundations of language. New York: Wiley.
- View Article
- Google Scholar
- 10. Long MH (2007) Problems in SLA. Mahwah, NJ: Lawrence Erlbaum.
- 14. DeKeyser R, Larson-Hall J (2005) What does the critical period really mean? In: Kroll and De Groot [75], 88–108.
- 19. Newport EL (1991) Contrasting conceptions of the critical period for language. In: Carey S, Gelman R, editors, The epigenesis of mind: Essays on biology and cognition, Hillsdale, NJ: Lawrence Erlbaum. 111–130.
- 20. Birdsong D (2005) Interpreting age effects in second language acquisition. In: Kroll and De Groot [75], 109–127.
- 22. DeKeyser R (2012) Age effects in second language learning. In: Gass SM, Mackey A, editors, The Routledge handbook of second language acquisition, London: Routledge. 442–460.
- 24. Weisstein EW. Discontinuity. From MathWorld –A Wolfram Web Resource. Available: http://mathworld.wolfram.com/Discontinuity.html . Accessed 2012 March 2.
- 27. Flege JE (1999) Age of learning and second language speech. In: Birdsong [76], 101–132.
- 36. Champely S (2009) pwr: Basic functions for power analysis. Available: http://cran.r-project.org/package=pwr . R package, version 1.1.1.
- 37. R Core Team (2013) R: A language and environment for statistical computing. Available: http://www.r-project.org/ . Software, version 2.15.3.
- 47. Hyltenstam K, Abrahamsson N (2003) Maturational constraints in sla . In: Doughty CJ, Long MH, editors, The handbook of second language acquisition, Malden, MA: Blackwell. 539–588.
- 49. Bialystok E, Hakuta K (1999) Confounded age: Linguistic and cognitive factors in age differences for second language acquisition. In: Birdsong [76], 161–181.
- 52. DeKeyser R (2006) A critique of recent arguments against the critical period hypothesis. In: Abello-Contesse C, Chacón-Beltrán R, López-Jiménez MD, Torreblanca-López MM, editors, Age in L2 acquisition and teaching, Bern: Peter Lang. 49–58.
- 55. Baayen RH (2008) Analyzing linguistic data: A practical introduction to statistics using R. Cambridge: Cambridge University Press.
- 56. Fox J (2002) Robust regression. Appendix to An R and S-Plus Companion to Applied Regression. Available: http://cran.r-project.org/doc/contrib/Fox-Companion/appendix.html .
- 57. Ripley B, Hornik K, Gebhardt A, Firth D (2012) MASS: Support functions and datasets for Venables and Ripley's MASS. Available: http://cran.r-project.org/package=MASS . R package, version 7.3–17.
- 58. Zuur AF, Ieno EN, Walker NJ, Saveliev AA, Smith GM (2009) Mixed effects models and extensions in ecology with R. New York: Springer.
- 59. Pinheiro J, Bates D, DebRoy S, Sarkar D, R Core Team (2013) nlme: Linear and nonlinear mixed effects models. Available: http://cran.r-project.org/package=nlme . R package, version 3.1–108.
- 65. Field A (2009) Discovering statistics using SPSS. London: SAGE 3rd edition.
- 66. Birdsong D (2009) Age and the end state of second language acquisition. In: Ritchie WC, Bhatia TK, editors, The new handbook of second language acquisition, Bingley: Emerlad. 401–424.
- 75. Kroll JF, De Groot AMB, editors (2005) Handbook of bilingualism: Psycholinguistic approaches. New York: Oxford University Press.
- 76. Birdsong D, editor (1999) Second language acquisition and the critical period hypothesis. Mahwah, NJ: Lawrence Erlbaum.
- Search Menu
- Sign in through your institution
- Advance articles
- Editor's Choice
- Key Concepts
- The View From Here
- Author Guidelines
- Submission Site
- Open Access
- Why Publish?
- About ELT Journal
- Editorial Board
- Advertising and Corporate Services
- Journals Career Network
- Self-Archiving Policy
- Dispatch Dates
- Terms and Conditions
- Journals on Oxford Academic
- Books on Oxford Academic
Article Contents
- < Previous
Age and the critical period hypothesis
- Article contents
- Figures & tables
- Supplementary Data
Christian Abello-Contesse, Age and the critical period hypothesis, ELT Journal , Volume 63, Issue 2, April 2009, Pages 170–172, https://doi.org/10.1093/elt/ccn072
- Permissions Icon Permissions
In the field of second language acquisition (SLA), how specific aspects of learning a non-native language (L2) may be affected by when the process begins is referred to as the ‘age factor’. Because of the way age intersects with a range of social, affective, educational, and experiential variables, clarifying its relationship with learning rate and/or success is a major challenge.
There is a popular belief that children as L2 learners are ‘superior’ to adults ( Scovel 2000 ), that is, the younger the learner, the quicker the learning process and the better the outcomes. Nevertheless, a closer examination of the ways in which age combines with other variables reveals a more complex picture, with both favourable and unfavourable age-related differences being associated with early- and late-starting L2 learners ( Johnstone 2002 ).
The ‘critical period hypothesis’ (CPH) is a particularly relevant case in point. This is the claim that there is, indeed, an optimal period for language acquisition, ending at puberty. However, in its original formulation ( Lenneberg 1967 ), evidence for its existence was based on the relearning of impaired L1 skills, rather than the learning of a second language under normal circumstances.
Furthermore, although the age factor is an uncontroversial research variable extending from birth to death ( Cook 1995 ), and the CPH is a narrowly focused proposal subject to recurrent debate, ironically, it is the latter that tends to dominate SLA discussions ( García Lecumberri and Gallardo 2003 ), resulting in a number of competing conceptualizations. Thus, in the current literature on the subject ( Bialystok 1997 ; Richards and Schmidt 2002 ; Abello-Contesse et al. 2006), references can be found to (i) multiple critical periods (each based on a specific language component, such as age six for L2 phonology), (ii) the non-existence of one or more critical periods for L2 versus L1 acquisition, (iii) a ‘sensitive’ yet not ‘critical’ period, and (iv) a gradual and continual decline from childhood to adulthood.
It therefore needs to be recognized that there is a marked contrast between the CPH as an issue of continuing dispute in SLA, on the one hand, and, on the other, the popular view that it is an invariable ‘law’, equally applicable to any L2 acquisition context or situation. In fact, research indicates that age effects of all kinds depend largely on the actual opportunities for learning which are available within overall contexts of L2 acquisition and particular learning situations, notably the extent to which initial exposure is substantial and sustained ( Lightbown 2000 ).
Thus, most classroom-based studies have shown not only a lack of direct correlation between an earlier start and more successful/rapid L2 development but also a strong tendency for older children and teenagers to be more efficient learners. For example, in research conducted in the context of conventional school programmes, Cenoz (2003) and Muñoz (2006) have shown that learners whose exposure to the L2 began at age 11 consistently displayed higher levels of proficiency than those for whom it began at 4 or 8. Furthermore, comparable limitations have been reported for young learners in school settings involving innovative, immersion-type programmes, where exposure to the target language is significantly increased through subject-matter teaching in the L2 ( Genesee 1992 ; Abello-Contesse 2006 ). In sum, as Harley and Wang (1997) have argued, more mature learners are usually capable of making faster initial progress in acquiring the grammatical and lexical components of an L2 due to their higher level of cognitive development and greater analytical abilities.
In terms of language pedagogy, it can therefore be concluded that (i) there is no single ‘magic’ age for L2 learning, (ii) both older and younger learners are able to achieve advanced levels of proficiency in an L2, and (iii) the general and specific characteristics of the learning environment are also likely to be variables of equal or greater importance.
Google Scholar
Google Preview
Month: | Total Views: |
---|---|
November 2016 | 31 |
December 2016 | 27 |
January 2017 | 31 |
February 2017 | 151 |
March 2017 | 238 |
April 2017 | 217 |
May 2017 | 355 |
June 2017 | 190 |
July 2017 | 91 |
August 2017 | 126 |
September 2017 | 264 |
October 2017 | 449 |
November 2017 | 743 |
December 2017 | 2,636 |
January 2018 | 2,610 |
February 2018 | 2,558 |
March 2018 | 3,166 |
April 2018 | 3,303 |
May 2018 | 3,359 |
June 2018 | 2,511 |
July 2018 | 2,078 |
August 2018 | 2,265 |
September 2018 | 2,635 |
October 2018 | 2,792 |
November 2018 | 3,935 |
December 2018 | 3,107 |
January 2019 | 2,182 |
February 2019 | 2,369 |
March 2019 | 3,416 |
April 2019 | 3,041 |
May 2019 | 2,845 |
June 2019 | 2,220 |
July 2019 | 2,079 |
August 2019 | 2,154 |
September 2019 | 2,452 |
October 2019 | 2,578 |
November 2019 | 2,371 |
December 2019 | 1,968 |
January 2020 | 1,602 |
February 2020 | 1,679 |
March 2020 | 1,768 |
April 2020 | 2,161 |
May 2020 | 1,377 |
June 2020 | 1,934 |
July 2020 | 1,221 |
August 2020 | 1,264 |
September 2020 | 1,773 |
October 2020 | 2,082 |
November 2020 | 2,169 |
December 2020 | 2,161 |
January 2021 | 1,988 |
February 2021 | 1,588 |
March 2021 | 1,974 |
April 2021 | 1,892 |
May 2021 | 1,617 |
June 2021 | 1,224 |
July 2021 | 981 |
August 2021 | 983 |
September 2021 | 1,286 |
October 2021 | 1,714 |
November 2021 | 1,757 |
December 2021 | 1,510 |
January 2022 | 1,419 |
February 2022 | 1,028 |
March 2022 | 1,344 |
April 2022 | 993 |
May 2022 | 947 |
June 2022 | 698 |
July 2022 | 534 |
August 2022 | 337 |
September 2022 | 496 |
October 2022 | 836 |
November 2022 | 817 |
December 2022 | 701 |
January 2023 | 682 |
February 2023 | 419 |
March 2023 | 636 |
April 2023 | 706 |
May 2023 | 656 |
June 2023 | 422 |
July 2023 | 709 |
August 2023 | 343 |
September 2023 | 411 |
October 2023 | 619 |
November 2023 | 751 |
December 2023 | 501 |
January 2024 | 534 |
February 2024 | 345 |
March 2024 | 685 |
April 2024 | 671 |
May 2024 | 687 |
June 2024 | 388 |
July 2024 | 370 |
August 2024 | 103 |
Email alerts
Citing articles via.
- Recommend to Your Library
Affiliations
- Online ISSN 1477-4526
- Print ISSN 0951-0893
- Copyright © 2024 Oxford University Press
- About Oxford Academic
- Publish journals with us
- University press partners
- What we publish
- New features
- Open access
- Institutional account management
- Rights and permissions
- Get help with access
- Accessibility
- Advertising
- Media enquiries
- Oxford University Press
- Oxford Languages
- University of Oxford
Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide
- Copyright © 2024 Oxford University Press
- Cookie settings
- Cookie policy
- Privacy policy
- Legal notice
This Feature Is Available To Subscribers Only
Sign In or Create an Account
This PDF is available to Subscribers Only
For full access to this pdf, sign in to an existing account, or purchase an annual subscription.
- Subject List
- Take a Tour
- For Authors
- Subscriber Services
- Publications
- African American Studies
- African Studies
- American Literature
- Anthropology
- Architecture Planning and Preservation
- Art History
- Atlantic History
- Biblical Studies
- British and Irish Literature
- Childhood Studies
- Chinese Studies
- Cinema and Media Studies
- Communication
- Criminology
- Environmental Science
- Evolutionary Biology
- International Law
- International Relations
- Islamic Studies
- Jewish Studies
- Latin American Studies
- Latino Studies
Linguistics
- Literary and Critical Theory
- Medieval Studies
- Military History
- Political Science
- Public Health
- Renaissance and Reformation
- Social Work
- Urban Studies
- Victorian Literature
- Browse All Subjects
How to Subscribe
- Free Trials
In This Article Expand or collapse the "in this article" section Critical Periods
Introduction, general overviews.
- Critical Periods in Language: Background Readings
- First-Language Acquisition (L1A)
- Age and Second-Language Acquisition (L2A)
- Controversy around the Critical Period Hypothesis for Second-Language Acquisition (CPH/L2A)
- Critical Period Geometry and Timing in L2A
- Brain-Based Studies of Critical Periods in L2A
- Bilingualism
- First-Language Attrition
- Sign Language
- Foreign Language Education
- Animal Models of Critical Periods
- Absolute Pitch
Related Articles Expand or collapse the "related articles" section about
About related articles close popup.
Lorem Ipsum Sit Dolor Amet
Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aliquam ligula odio, euismod ut aliquam et, vestibulum nec risus. Nulla viverra, arcu et iaculis consequat, justo diam ornare tellus, semper ultrices tellus nunc eu tellus.
- Acceptability Judgments
- Acquisition of Possessives
- Acquisition of Pragmatics
- Bilingualism and Multilingualism
- Biology of Language
- Children’s Acquisition of Syntactic Knowledge
- Early Child Phonology
- Experimental Linguistics
- Genetics and Language
- Language Acquisition
- Language in Autism Spectrum Disorders
- Language Nests
- Learnability
- Psycholinguistic Perspectives on Second Language Acquisition and Bilingualism
- Roman Jakobson
- The Prague Linguistic Circle
- Variationist Sociolinguistics
- Visual Word Recognition
Other Subject Areas
Forthcoming articles expand or collapse the "forthcoming articles" section.
- Edward Sapir
- Sentence Comprehension
- Text Comprehension
- Find more forthcoming articles...
- Export Citations
- Share This Facebook LinkedIn Twitter
Critical Periods by David P. Birdsong LAST REVIEWED: 12 January 2023 LAST MODIFIED: 12 January 2023 DOI: 10.1093/obo/9780199772810-0139
A critical period is a bounded maturational span during which experiential factors interact with biological mechanisms to determine neurocognitive and behavioral outcomes. In humans, the construct of critical period (CP) is commonly applied to first-language (L1) and second-language (L2) development. Some language researchers hold that during a CP, various mechanisms are at work that result in successful language acquisition and language processing. Outside of the period, other factors and mechanisms are involved, resulting in deficits in acquisition and processing. Many researchers believe that L1 development is constrained by maturationally based CPs. However, this notion is more controversial in L2 acquisition research, where the Critical Period Hypothesis for L2 acquisition (CPH/L2A) is debated on empirical, theoretical, and methodological grounds. Bilingualism researchers study the possibility that CPs may govern the likelihood and degree of loss (attrition) of the L1 among bilinguals as they age. Studies of CPs in L1 acquisition and L2 acquisition have been conducted with learners of spoken languages, signed languages, and artificial languages. CP research is considered in educational policy, particularly in the context of foreign language instruction. On a terminological note, a distinction is sometimes drawn between “critical” and “sensitive” periods, the latter term denoting receptivity of the organism to shaping by experience (or, in certain studies, suggesting relatively mild effects). Some researchers use these terms interchangeably, while others use one but not the other. Here, “critical period” will be used as a cover term unless specific reference is being made to sensitive period.
Lillard and Erisir 2011 describes juvenile CPs in language, imprinting, and vision. The article includes an informative table covering seven levels of neural changes in the brain in juveniles versus adults, with notes on the time course of changes and affected brain areas in animal and human models. The authors observe that changes in neural architecture triggered by early versus late experiences differ in degree more than type, and that the variety of triggering experiences is reduced with age. A second table summarizes neuroanatomical, electrophysiological, and neuroimaging techniques for observing specific types of neuroplasticity. Knudsen 2004 is exceptionally informative with respect to: prerequisites for CPs; the properties, mechanisms, and timing of plasticity; reopening of critical periods; the roles of presence and absence of relevant stimulation; and sensitive periods versus critical periods. Knudsen points out that complex behaviors (which include language use) may be regulated by multiple CPs. Takesian and Hensch 2013 emphasizes the individual-level plasticity of the timing of CP onset, peak, and offset, which may vary according to excitatory/inhibitory circuit balance that is sensitive to drugs, sleep, trauma, and genetic perturbation (see also Werker and Hensch 2015 [cited under First-Language Acquisition (L1A) ). Reh, et al. 2020 examines how plasticity is regulated at multiple timescales during development and provides examples from language processing, mental illness, and recovery from brain injury. Gabard-Durnam and McLaughlin 2020 outlines a set of current approaches to the study of sensitive periods in humans. These approaches include environmental manipulations (deprivation, enrichment, substitution), plasticity manipulations via pharmacological intervention, and computational modeling. Frankenhuis and Walasek 2020 develops an evolutionary model that accounts for sensitive periods that occur beyond the early stages of ontogeny.
Frankenhuis, Willem E., and Nicole Walasek. 2020. Modeling the evolution of sensitive periods . Developmental Cognitive Neuroscience 41:100715.
DOI: 10.1016/j.dcn.2019.100715
Sensitive periods in mid-ontogeny are favored by natural selection as a function of the reliability of relevant environmental cues.
Gabard-Durnam, Laurel, and Katie A. McLaughlin. 2020. Sensitive periods in human development: Charting a course for the future. Current Opinion in Behavioral Sciences 36:120–128.
DOI: 10.1016/j.cobeha.2020.09.003
Figures 1, 2 and 3 and their captions are particularly informative.
Knudsen, Eric I. 2004. Sensitive periods in the development of brain and behavior. Journal of Cognitive Neuroscience 16.8: 1412–1425.
DOI: 10.1162/0898929042304796
Focuses on the role of experience in modifying neural circuits during periods of plasticity, leading to connectivity patterns that become stable and less energy intensive, and making up what Knudsen calls the “stability landscape.”
Lillard, Angeline S., and Alev Erisir. 2011. Old dogs learning new tricks: Neuroplasticity beyond the juvenile period. Developmental Review 31:207–239.
DOI: 10.1016/j.dr.2011.07.008
A largely uncritical review and synthesis of well-known studies.
Reh, Rebecca K., Brian G. Dias, Charles A. Nelson III, et al. 2020. Critical period regulation across multiple timescales . Proceedings of the National Academy of Sciences of the United States of America 117.38: 23242–23251.
DOI: 10.1073/pnas.1820836117
A diverse group of specialists’ account of neurobiological CP mechanisms in animals and humans. Notes that “cortical plasticity is not only influenced by an animal’s life experiences but may also be modified by that of the parents. This occurs via parental behavior during the offspring’s early postnatal life, the in utero environment during gestation, or modification of the parental or fetal germ cells” (p. 23246).
Takesian, Anne E., and Takao K. Hensch. 2013. Balancing plasticity/stability across brain development. Progress in Brain Research 207:3–34.
DOI: 10.1016/B978-0-444-63327-9.00001-1
Illuminates the dynamic between the intrinsic plasticity of CP and the stabilization of neural networks, which limits maladaptive proliferation of circuit rewiring past the CP.
back to top
Users without a subscription are not able to see the full content on this page. Please subscribe or login .
Oxford Bibliographies Online is available by subscription and perpetual access to institutions. For more information or to contact an Oxford Sales Representative click here .
- About Linguistics »
- Meet the Editorial Board »
- Accessibility Theory in Linguistics
- Acquisition, Second Language, and Bilingualism, Psycholin...
- Adpositions
- African Linguistics
- Afroasiatic Languages
- Algonquian Linguistics
- Altaic Languages
- Ambiguity, Lexical
- Analogy in Language and Linguistics
- Animal Communication
- Applicatives
- Applied Linguistics, Critical
- Arawak Languages
- Argument Structure
- Artificial Languages
- Australian Languages
- Austronesian Linguistics
- Auxiliaries
- Balkans, The Languages of the
- Baudouin de Courtenay, Jan
- Berber Languages and Linguistics
- Borrowing, Structural
- Caddoan Languages
- Caucasian Languages
- Celtic Languages
- Celtic Mutations
- Chomsky, Noam
- Chumashan Languages
- Classifiers
- Clauses, Relative
- Clinical Linguistics
- Cognitive Linguistics
- Colonial Place Names
- Comparative Reconstruction in Linguistics
- Comparative-Historical Linguistics
- Complementation
- Complexity, Linguistic
- Compositionality
- Compounding
- Computational Linguistics
- Conditionals
- Conjunctions
- Connectionism
- Consonant Epenthesis
- Constructions, Verb-Particle
- Contrastive Analysis in Linguistics
- Conversation Analysis
- Conversation, Maxims of
- Conversational Implicature
- Cooperative Principle
- Coordination
- Creoles, Grammatical Categories in
- Critical Periods
- Cross-Language Speech Perception and Production
- Cyberpragmatics
- Default Semantics
- Definiteness
- Dementia and Language
- Dene (Athabaskan) Languages
- Dené-Yeniseian Hypothesis, The
- Dependencies
- Dependencies, Long Distance
- Derivational Morphology
- Determiners
- Dialectology
- Distinctive Features
- Dravidian Languages
- Endangered Languages
- English as a Lingua Franca
- English, Early Modern
- English, Old
- Eskimo-Aleut
- Euphemisms and Dysphemisms
- Evidentials
- Exemplar-Based Models in Linguistics
- Existential
- Existential Wh-Constructions
- Fieldwork, Sociolinguistic
- Finite State Languages
- First Language Attrition
- Formulaic Language
- Francoprovençal
- French Grammars
- Gabelentz, Georg von der
- Genealogical Classification
- Generative Syntax
- Grammar, Categorial
- Grammar, Cognitive
- Grammar, Construction
- Grammar, Descriptive
- Grammar, Functional Discourse
- Grammars, Phrase Structure
- Grammaticalization
- Harris, Zellig
- Heritage Languages
- History of Linguistics
- History of the English Language
- Hmong-Mien Languages
- Hokan Languages
- Humor in Language
- Hungarian Vowel Harmony
- Idiom and Phraseology
- Imperatives
- Indefiniteness
- Indo-European Etymology
- Inflected Infinitives
- Information Structure
- Interface Between Phonology and Phonetics
- Interjections
- Iroquoian Languages
- Isolates, Language
- Jakobson, Roman
- Japanese Word Accent
- Jones, Daniel
- Juncture and Boundary
- Khoisan Languages
- Kiowa-Tanoan Languages
- Kra-Dai Languages
- Labov, William
- Language and Law
- Language Contact
- Language Documentation
- Language, Embodiment and
- Language for Specific Purposes/Specialized Communication
- Language, Gender, and Sexuality
- Language Geography
- Language Ideologies and Language Attitudes
- Language Revitalization
- Language Shift
- Language Standardization
- Language, Synesthesia and
- Languages of Africa
- Languages of the Americas, Indigenous
- Languages of the World
- Lexical Access, Cognitive Mechanisms for
- Lexical Semantics
- Lexical-Functional Grammar
- Lexicography
- Lexicography, Bilingual
- Linguistic Accommodation
- Linguistic Anthropology
- Linguistic Areas
- Linguistic Landscapes
- Linguistic Prescriptivism
- Linguistic Profiling and Language-Based Discrimination
- Linguistic Relativity
- Linguistics, Educational
- Listening, Second Language
- Literature and Linguistics
- Machine Translation
- Maintenance, Language
- Mande Languages
- Mass-Count Distinction
- Mathematical Linguistics
- Mayan Languages
- Mental Health Disorders, Language in
- Mental Lexicon, The
- Mesoamerican Languages
- Minority Languages
- Mixed Languages
- Mixe-Zoquean Languages
- Modification
- Mon-Khmer Languages
- Morphological Change
- Morphology, Blending in
- Morphology, Subtractive
- Munda Languages
- Muskogean Languages
- Nasals and Nasalization
- Niger-Congo Languages
- Non-Pama-Nyungan Languages
- Northeast Caucasian Languages
- Oceanic Languages
- Papuan Languages
- Penutian Languages
- Philosophy of Language
- Phonetics, Acoustic
- Phonetics, Articulatory
- Phonological Research, Psycholinguistic Methodology in
- Phonology, Computational
- Phonology, Early Child
- Policy and Planning, Language
- Politeness in Language
- Positive Discourse Analysis
- Possessives, Acquisition of
- Pragmatics, Acquisition of
- Pragmatics, Cognitive
- Pragmatics, Computational
- Pragmatics, Cross-Cultural
- Pragmatics, Developmental
- Pragmatics, Experimental
- Pragmatics, Game Theory in
- Pragmatics, Historical
- Pragmatics, Institutional
- Pragmatics, Second Language
- Pragmatics, Teaching
- Prague Linguistic Circle, The
- Presupposition
- Psycholinguistics
- Quechuan and Aymaran Languages
- Reading, Second-Language
- Reciprocals
- Reduplication
- Reflexives and Reflexivity
- Register and Register Variation
- Relevance Theory
- Representation and Processing of Multi-Word Expressions in...
- Salish Languages
- Sapir, Edward
- Saussure, Ferdinand de
- Second Language Acquisition, Anaphora Resolution in
- Semantic Maps
- Semantic Roles
- Semantic-Pragmatic Change
- Semantics, Cognitive
- Sentence Processing in Monolingual and Bilingual Speakers
- Sign Language Linguistics
- Sociolinguistics
- Sociolinguistics, Variationist
- Sociopragmatics
- Sound Change
- South American Indian Languages
- Specific Language Impairment
- Speech, Deceptive
- Speech Perception
- Speech Production
- Speech Synthesis
- Switch-Reference
- Syntactic Change
- Syntactic Knowledge, Children’s Acquisition of
- Tense, Aspect, and Mood
- Text Mining
- Tone Sandhi
- Transcription
- Transitivity and Voice
- Translanguaging
- Translation
- Trubetzkoy, Nikolai
- Tucanoan Languages
- Tupian Languages
- Usage-Based Linguistics
- Uto-Aztecan Languages
- Valency Theory
- Verbs, Serial
- Vocabulary, Second Language
- Voice and Voice Quality
- Vowel Harmony
- Whitney, William Dwight
- Word Classes
- Word Formation in Japanese
- Word Recognition, Spoken
- Word Recognition, Visual
- Word Stress
- Writing, Second Language
- Writing Systems
- Zapotecan Languages
- Privacy Policy
- Cookie Policy
- Legal Notice
- Accessibility
Powered by:
- [81.177.180.204]
- 81.177.180.204
The Critical Period Hypothesis for Second Language Acquisition: Tailoring the Coat of Many Colors
- First Online: 01 January 2013
Cite this chapter
- David Birdsong 4
Part of the book series: Second Language Learning and Teaching ((SLLT))
3200 Accesses
16 Citations
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.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Subscribe and save.
- Get 10 units per month
- Download Article/Chapter or eBook
- 1 Unit = 1 Article or 1 Chapter
- Cancel anytime
- Available as PDF
- Read on any device
- Instant download
- Own it forever
- Available as EPUB and PDF
- Compact, lightweight edition
- Dispatched in 3 to 5 business days
- Free shipping worldwide - see info
- Durable hardcover edition
Tax calculation will be finalised at checkout
Purchases are for personal use only
Institutional subscriptions
Similar content being viewed by others
Second Language Acquisition Research Methods
The Socio-educational Model of Second Language Acquisition
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).
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.
Abrahamsson, N. and K. Hyltenstam. 2009. Age of onset and nativelikeness in a second language: Listener perception versus linguistic scrutiny. Language Learning 59: 249–306.
Google Scholar
Ayer, A. J. 1959. History of the Logical Positivist movement. In Logical Positivism , ed. A. J. Ayer, 3–28. New York: Free Press.
Birdsong, D. 2005. Interpreting age effects in second language acquisition. In Handbook of bilingualism , eds. J. Kroll and A. DeGroot, 109–127. Oxford: Oxford University Press.
Birdsong, D. and M. Molis. 2001. On the evidence for maturational constraints in second-language acquisition. Journal of Memory and Language 44: 235–249.
Carroll, J. B. and S. M. Sapon. 1959. Modern Language Aptitude Test: Manual. New York: Psychological Corporation.
Cook, V. 2003. Effects of the second language on the first. Clevedon, UK: Multilingual Matters.
DeKeyser, R. M. 2000. The robustness of critical period effects in second language acquisition. Studies in Second Language Acquisition 22: 499–533.
DeKeyser, R., I. Alfi-Shabtay and D. Ravid. 2010. Cross-linguistic evidence for the nature of age effects in second language acquisition. Applied Psycholinguistics 31: 413–438.
Fowler, C. A., V. Sramko, D. J. Ostry, S. A. Rowland and P. Hallé. 2008. Cross language phonetic influences on the speech of French-English bilinguals. Journal of Phonetics 36: 649–663.
Granena, G. and M. H. Long. 2013. Age of onset, length of residence, language aptitude, and ultimate L2 attainment in three linguistic domains. Second Language Research 29: 311–343.
Hakuta, K., E. Bialystok and E. Wiley. 2003. Critical evidence: A test of the Critical-Period Hypothesis for second-language acquisition. Psychological Science 14: 31–38.
Hyltenstam, K. and N. Abrahamsson. 2003. Maturational constraints in SLA. The handbook of second language acquisition , eds. M. H. Long and C. J. Doughty, 539–588. Malden, MA: Blackwell.
Johnson, J. S. and E. L. Newport. 1989. Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology 21: 60–99.
Lenneberg, E. H. 1967. Biological foundations of language. New York: Wiley.
Long, M. H. 1990. Maturational constraints on language development. Studies in Second Language Acquisition 12: 251–285.
Ortega, L. 2009. Understanding second language acquisition. London: Hodder Education.
Penfield, W. and L. Roberts. 1959. Speech and brain mechanisms. Princeton, NJ: Princeton University Press.
Popper, K. 1959. The logic of scientific discovery . New York: Basic Books.
Singleton, D. 2005. The Critical Period Hypothesis: A coat of many colours. International Review of Applied Linguistics in Language Teaching 43: 269–285.
Stevens, G. 2004. Using census data to test the critical-period hypothesis for second-language acquisition. Psychological Science 15: 215–216.
Vanhove, J. 2013. The critical period hypothesis in second language acquisition: A statistical critique and a reanalysis. PLoS ONE. 8(7): e69172. doi: 10.137/journal.pone.0069172
Download references
Author information
Authors and affiliations.
University of Texas at Austin, Texas, USA
David Birdsong
You can also search for this author in PubMed Google Scholar
Corresponding author
Correspondence to David Birdsong .
Editor information
Editors and affiliations.
Faculty of Pedagogy and Fine Arts Dept. of English Studies, Adam Mickiewicz University, Kalisz, Wielkopolskie, Poland
Mirosław Pawlak
Graduate Studies Faculty, Oranim Academic College of Education, Tivon, Israel
Larissa Aronin
Rights and permissions
Reprints and permissions
Copyright information
© 2014 Springer International Publishing Switzerland
About this chapter
Birdsong, D. (2014). The Critical Period Hypothesis for Second Language Acquisition: Tailoring the Coat of Many Colors. In: Pawlak, M., Aronin, L. (eds) Essential Topics in Applied Linguistics and Multilingualism. Second Language Learning and Teaching. Springer, Cham. https://doi.org/10.1007/978-3-319-01414-2_3
Download citation
DOI : https://doi.org/10.1007/978-3-319-01414-2_3
Published : 19 September 2013
Publisher Name : Springer, Cham
Print ISBN : 978-3-319-01413-5
Online ISBN : 978-3-319-01414-2
eBook Packages : Humanities, Social Sciences and Law Education (R0)
Share this chapter
Anyone you share the following link with will be able to read this content:
Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative
- Publish with us
Policies and ethics
- Find a journal
- Track your research
Multilingual Pedagogy and World Englishes
Linguistic Variety, Global Society
![critical period hypothesis in language development Multilingual Pedagogy and World Englishes](https://worldenglishes.lmc.gatech.edu/wp-content/uploads/sites/24/2019/06/cropped-cropped-4096px-Whole_world_-_land_and_oceans_12000-2-2.jpg)
Critical Period Hypothesis (CPH)
Tom Scovel writes, “The CPH [critical period hypothesis] is conceivably the most contentious issue in SLA because there is disagreement over its exact age span; people disagree strenuously over which facets of language are affected; there are competing explanations for its existence; and, to top it off, many people don’t believe it exists at all” (113). Proposed by Wilder Penfield and Lamar Roberts in 1959, the Critical Period Hypothesis (CPH) argues that there is a specific period of time in which people can learn a language without traces of the L1 (a so-called “foreign” accent or even L1 syntactical features) manifesting in L2 production (Scovel 48). If a learner’s goal is to sound “native,” there may be age-related limitations or “maturational constraints” as Kenneth Hyltenstam and Niclas Abrahamsson call them, on how “native” they can sound. Reducing the impression left by the L1 is certainly possible after puberty, but eliminating that impression entirely may not be possible.
Kenji Hakuta et al. explains that the relationship between age and L1 interference in L2 production is really not up for debate:
“The diminished average achievement of older learners is supported by personal anecdote and documented by empirical evidence….What is controversial, though, is whether this pattern meets the conditions for concluding that a critical period constrains learning in a way predicted by the theory” (31).
Some learners manage to overcome the “constraints” that Scovel believes are “probably accounted for by neurological factors that are genetically specified in our species” (114), but these learners are exceptional rather than the rule. It may be biology; it may be due to something else. The debate will continue, but evidence seems to indicate that the older learners become, the more difficult complete acquisition can be.
“David Birdsong, Looking Inside and Beyond the Critical Period Hypothesis.” YouTube, uploaded by IWL Channel, 09 May 2016, https://www.youtube.com/watch?v=9Bo0C4dj7Mw.
Application
Instructors should consider taking the CPH into account when assessing their students’ oral communication in the target language. When “maturational constraints” are a potential concern, it seems more fair for instructors to weight comprehension more heavily than nativeness. A thorough understanding of the CPH can also help instructors to counteract adult learners’ “self-handicapping” by helping the learners understand that, in spite of constraints due to aging, they are still capable of acquiring many–if not most–aspects of the target language.
Bibliography
Hakuta, Kenji, et al. “Critical Evidence: A Test of the Critical-Period Hypothesis for Second-Language Acquisition.” Psychological Science , vol. 14, no. 1, 2003, pp. 31–38. JSTOR , www.jstor.org/stable/40063748.
Hyltenstam, Kenneth, and Niclas Abrahamsson. “Comments on Stefka H. Marinova-Todd, D. Bradford Marshall, and Catherine E. Snow’s ‘Three Misconceptions about Age and L2 Learning’: Age and L2 Learning: The Hazards of Matching Practical ‘Implications’ with Theoretical ‘Facts.’” TESOL Quarterly , vol. 35, no. 1, 2001, pp. 151–170. JSTOR , www.jstor.org/stable/3587863.
Nemer, Randa. “Critical Period Hypothesis.” Prezi, 04 Dec. 2013, https://prezi.com/zzuch40ibrlq/critical-period-hypothesis-sla/#.
Scovel, Tom. Learning New Languages . Heinle & Heinle, 2001.
![](http://ortec.site/777/templates/cheerup1/res/banner1.gif)
Critical Period In Brain Development and Childhood Learning
Charlotte Nickerson
Research Assistant at Harvard University
Undergraduate at Harvard University
Charlotte Nickerson is a student at Harvard University obsessed with the intersection of mental health, productivity, and design.
Learn about our Editorial Process
Saul McLeod, PhD
Editor-in-Chief for Simply Psychology
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Olivia Guy-Evans, MSc
Associate Editor for Simply Psychology
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
On This Page:
Key Takeaways
- Critical period is an ethological term that refers to a fixed and crucial time during the early development of an organism when it can learn things that are essential to survival. These influences impact the development of processes such as hearing and vision, social bonding, and language learning.
- The term is most often experienced in the study of imprinting, where it is thought that young birds could only develop an attachment to the mother during a fixed time soon after hatching.
- Neurologically, critical periods are marked by high levels of plasticity in the brain before neural connections become more solidified and stable. In particular, critical periods tend to end when synapses that inhibit the neurotransmitter GABA mature.
- In contrast to critical periods, sensitive periods, otherwise known as “weak critical periods,” happen when an organism is more sensitive than usual to outside factors influencing behavior, but this influence is not necessarily restricted to the sensitive period.
- Scholars have debated the extent to which older organisms can develop certain skills, such as natively-accented foreign languages, after the critical period.
![Critical Period In Brain Development and Childhood Learning 1 brain critical development](https://www.simplypsychology.org/wp-content/uploads/brain-critical-development.jpg)
The critical period is a biologically determined stage of development where an organism is optimally ready to acquire some pattern of behavior that is part of typical development. This period, by definition, will not recur at a later stage.
If an organism does not receive exposure to the appropriate stimulus needed to learn a skill during a critical period, it may be difficult or even impossible for that organism to develop certain functions associated with that skill later in life.
This happens because a range of functional and structural elements prevent passive experiences from eliciting significant changes in the brain (Cisneros-Franco et al., 2020).
The first strong proponent of the theory of critical periods was Charles Stockhard (1921), a biologist who attempted to experiment with the effects of various chemicals on the development of fish embryos, though he gave credit to Dareste for originating the idea 30 years earlier (Scott, 1962).
Stockhard’s experiments showed that applying almost any chemical to fish embryos at a certain stage of development would result in one-eyed fish.
These experiments established that the most rapidly growing tissues in an embryo are the most sensitive to any change in conditions, leading to effects later in development (Scott, 1962).
Meanwhile, psychologist Sigmund Freud attempted to explain the origins of neurosis in human patients as the result of early experiences, implying that infants are particularly sensitive to influences at certain points in their lives.
Lorenz (1935) later emphasized the importance of critical periods in the formation of primary social bonds (otherwise known as imprinting) in birds, remarking that this psychological imprinting was similar to critical periods in the development of the embryo.
Soon thereafter, McGraw (1946) pointed out the existence of critical periods for the optimal learning of motor skills in human infants (Scott, 1962).
Example: Infant-Parent Attachment
The concept of critical or sensitive periods can also be found in the domain of social development, for example, in the formation of the infant-parent attachment relationship (Salkind, 2005).
Attachment describes the strong emotional ties between the infant and caregiver, a reciprocal relationship developing over the first year of the child’s life and particularly during the second six months of the first year.
During this attachment period , the infant’s social behavior becomes increasingly focused on the principal caregivers (Salkind, 2005).
The 20th-century English psychiatrist John Bowlby formulated and presented a comprehensive theory of attachment influenced by evolutionary theory.
Bowlby argued that the infant-parent attachment relationship develops because it is important to the survival of the infant and that the period from six to twenty-four months of age is a critical period of attachment.
This coincides with an infant’s increasing tendency to approach familiar caregivers and to be wary of unfamiliar adults. After this critical period, it is still possible for a first attachment relationship to develop, albeit with greater difficulty (Salkind, 2005).
This has brought into question, in a similar vein to language development, whether there is actually a critical development period for infant-caregiver attachment.
Sources debating this issue typically include cases of infants who did not experience consistent caregiving due to being raised in institutions prior to adoption (Salkind, 2005).
Early research into the critical period of attachment, published in the 1940s, reports consistently that children raised in orphanages subsequently showed unusual and maladaptive patterns of social behavior, difficulty in forming close relationships, and being indiscriminately friendly toward unfamiliar adults (Salkind, 2005).
Later, research from the 1990s indicated that adoptees were actually still able to form attachment relationships after the first year of life and also made developmental progress following adoption.
Nonetheless, these children had an overall increased risk of insecure or maladaptive attachment relationships with their adoptive parents. This evidence supports the notion of a sensitive period, but not a critical period, in the development of first attachment relationships (Salkind, 2005).
Mechanisms for Critical Periods
Both genetics and sensory experiences from outside the body shape the brain as it develops (Knudsen, 2004). However, the developmental stage that an organism is in significantly impacts how much the brain can change based on these experiences.
In scientific terms, the brain’s plasticity changes over the course of a lifespan. The brain is very plastic in the early stages of life before many key connections take root, but less so later.
This is why researchers have shown that early experience is crucial for the development of, say, language and musical abilities, and these skills are more challenging to take up in adulthood (Skoe and Kraus, 2013; White et al., 2013; Hartshorne et al., 2018).
As brains mature, the connections in them become more fixed. The brain’s transitions from a more plastic to a more fixed state advantageously allow it to retain new and complex processes, such as perceptual, motor, and cognitive functions (Piaget, 1962).
Children’s gestures, for example, pride and predict how they will acquire oral language skills (Colonnesi et al., 2010), which in turn are important for developing executive functions (Marcovitch and Zelazo, 2009).
However, this formation of stable connections in the brain can limit how the brain’s neural circuitry can be revised in the future. For example, if a young organism has abnormal sensory experiences during the critical period – such as auditory or visual deprivation – the brain may not wire itself in a way that processes future sensory inputs properly (Gallagher et al., 2020).
One illustration of this is the timing of cochlear implants – a prosthesis that restores hearing in some deaf people. Children who receive cochlear implants before two years of age are more likely to benefit from them than those who are implanted later in life (Kral and Eggermont, 2007; Gallagher et al., 2020).
Similarly, the visual deprivation caused by cataracts in infants can cause similar consequences. When cataracts are removed during early infancy, individuals can develop relatively normal vision; however, when the cataracts are not removed until adulthood, this results in substantially poorer vision (Martins Rosa et al., 2013).
After the critical period closes, abnormal sensory experiences have a less drastic effect on the brain and lead to – barring direct damage to the central nervous system – reversible changes (Gallagher et al., 2020). Much of what scientists know about critical periods derives from animal studies , as these allow researchers greater control over the variables that they are testing.
This research has found that different sensory systems, such as vision, auditory processing, and spatial hearing, have different critical periods (Gallagher et al., 2020).
The brain regulates when critical periods open and close by regulating how much the brain’s synapses take up neurotransmitters , which are chemical substances that affect the transmission of electrical signals between neurons.
In particular, over time, synapses decrease their uptake of gamma-aminobutyric acid, better known as GABA. At the beginning of the critical period, outside sources become more effective at influencing changes and growth in the brain.
Meanwhile, as the inhibitory circuits of the brain mature, the mature brain becomes less sensitive to sensory experiences (Gallagher et al., 2020).
Critical Periods vs Sensitive Periods
Critical periods are similar to sensitive periods, and scholars have, at times, used them interchangeably. However, they describe distinct but overlapping developmental processes.
A sensitive period is a developmental stage where sensory experiences have a greater impact on behavioral and brain development than usual; however, this influence is not exclusive to this time period (Knudsen, 2004; Gallagher, 2020). These sensitive periods are important for skills such as learning a language or instrument.
In contrast, A critical period is a special type of sensitive period – a window where sensory experience is necessary to shape the neural circuits involved in basic sensory processing, and when this window opens and closes is well-defined (Gallagher, 2020).
Researchers also refer to sensitive periods as weak critical periods. Some examples of strong critical periods include the development of vision and hearing, while weak critical periods include phenome tuning – how children learn how to organize sounds in a language, grammar processing, vocabulary acquisition, musical training, and sports training (Gallagher et al., 2020).
Critical Period Hypothesis
One of the most notable applications of the concept of a critical period is in linguistics. Scholars usually trace the origins of the debate around age in language acquisition to Penfield and Robert’s (2014) book Speech and Brain Mechanisms.
In the 1950s and 1960s, Penfield was a staunch advocate of early immersion education (Kroll and De Groot, 2009). Nonetheless, it was Lenneberg, in his book Biological Foundations of Language, who coined the term critical period (1967) in describing the language period.
Lennenberg (1967) described a critical period as a period of automatic acquisition from mere exposure” that “seems to disappear after this age.” Scovel (1969) later summarized and narrowed Penfield’s and Lenneberg’s view on the critical period hypothesis into three main claims:
- Adult native speakers can identify non-natives by their accents immediately and accurately.
- The loss of brain plasticity at about the age of puberty accounts for the emergence of foreign accents./li>
- The critical period hypothesis only holds for speech (whether or not someone has a native accent) and does not affect other areas of linguistic competence.
Linguists have since attempted to find evidence for whether or not scientific evidence actually supports the critical period hypothesis, if there is a critical period for acquiring accentless speech, for “morphosyntactic” competence, and if these are true, how age-related differences can be explained on the neurological level (Scovel, 2000).
The critical period hypothesis applies to both first and second-language learning. Until recently, research around the critical period’s role in first language acquisition revolved around findings about so-called “feral” children who had failed to acquire language at an older age after having been deprived of normal input during the critical period.
However, these case studies did not account for the extent to which social deprivation, and possibly food deprivation or sensory deprivation, may have confounded with language input deprivation (Kroll and De Groot, 2009).
More recently, researchers have focused more systematically on deaf children born to hearing parents who are therefore deprived of language input until at least elementary school.
These studies have found the effects of lack of language input without extreme social deprivation: the older the age of exposure to sign language is, the worse its ultimate attainment (Emmorey, Bellugi, Friederici, and Horn, 1995; Kroll and De Groot, 2009).
However, Kroll and De Groot argue that the critical period hypothesis does not apply to the rate of acquisition of language. Adults and adolescents can learn languages at the same rate or even faster than children in their initial stage of acquisition (Slavoff and Johnson, 1995).
However, adults tend to have a more limited ultimate attainment of language ability (Kroll and De Groot, 2009).
There has been a long lineage of empirical findings around the age of acquisition. The most fundamental of this research comes from a series of studies since the late 1970s documenting a negative correlation between age of acquisition and ultimate language mastery (Kroll and De Grott, 2009).
Nonetheless, different periods correspond to sensitivity to different aspects of language. For example, shortly after birth, infants can perceive and discriminate speech sounds from any language, including ones they have not been exposed to (Eimas et al., 1971; Gallagher et al., 2020).
Around six months of age, exposure to the primary language in the infant’s environment guides phonetic representations of language and, subsequently, the neural representations of speech sounds of the native language while weakening those of unused sounds (McClelland et al., 1999; Gallagher et al., 2020).
Vocabulary learning experiences rapid growth at about 18 months of age (Kuhl, 2010).
Critical Evaluation
More than any other area of applied linguistics, the critical period hypothesis has impacted how teachers teach languages. Consequently, researchers have critiqued how important the critical period is to language learning.
For example, several studies in early language acquisition research showed that children were not necessarily superior to older learners in acquiring a second language, even in the area of pronunciation (Olson and Samuels, 1973; Snow and Hoefnagel-Hohle, 1978; Scovel, 2000).
In fact, the majority of researchers at the time appeared to be skeptical about the existence of a critical period, with some explicitly denying its existence.
Counter to one of the primary tenets of Scovel’s (1969) critical period hypothesis, there have been several cases of people who have acquired a second language in adulthood speaking with native accents.
For example, Moyer’s study of highly proficient English-speaking learners of German suggested that at least one of the participants was judged to have native-like pronunciation in his second language (1999), and several participants in Bongaerts (1999) study of highly proficient Dutch speakers of French spoke with accents judged to be native (Scovel, 2000).
Bongaerts, T. (1999). Ultimate attainment in L2 pronunciation: The case of very advanced late L2 learners. Second language acquisition and the critical period hypothesis, 133-159.
Cisneros-Franco, J. M., Voss, P., Thomas, M. E., & de Villers-Sidani, E. (2020). Critical periods of brain development. In Handbook of Clinical Neurolog y (Vol. 173, pp. 75-88). Elsevier.
Colonnesi, C., Stams, G. J. J., Koster, I., & Noom, M. J. (2010). The relation between pointing and language development: A meta-analysis. Developmental Review, 30 (4), 352-366.
Eimas, P. D., Siqueland, E. R., Jusczyk, P., & Vigorito, J. (1971). Speech perception in infants. Science, 171 (3968), 303-306.
Emmorey, K., Bellugi, U., Friederici, A., & Horn, P. (1995). Effects of age of acquisition on grammatical sensitivity: Evidence from on-line and off-line tasks. Applied Psycholinguistics, 16 (1), 1-23.
Knudsen, E. I. (2004). Sensitive periods in the development of the brain and behavior. Journal of cognitive neuroscience, 16 (8), 1412-1425.
Hartshorne, J. K., Tenenbaum, J. B., & Pinker, S. (2018). A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition, 177 , 263-277.
Kral, A., & Eggermont, J. J. (2007). What’s to lose and what’s to learn: development under auditory deprivation, cochlear implants and limits of cortical plasticity. Brain Research Reviews, 56(1), 259-269.
Kroll, J. F., & De Groot, A. M. (Eds.). (2009). Handbook of bilingualism: Psycholinguistic approaches . Oxford University Press.
Kuhl, P. K. (2010). Brain mechanisms in early language acquisition. Neuron, 67 (5), 713-727.
Lenneberg, E. H. (1967). The biological foundations of language. Hospital Practice, 2( 12), 59-67.
Lorenz, K. (1935). Der kumpan in der umwelt des vogels. Journal für Ornithologie, 83 (2), 137-213.
Marcovitch, S., & Zelazo, P. D. (2009). A hierarchical competing systems model of the emergence and early development of executive function. Developmental science, 12 (1), 1-18.
McClelland, J. L., Thomas, A. G., McCandliss, B. D., & Fiez, J. A. (1999). Understanding failures of learning: Hebbian learning, competition for representational space, and some preliminary experimental data. Progress in brain research, 121, 75-80.
McGraw, M. B. (1946). Maturation of behavior. In Manual of child psychology. (pp. 332-369). John Wiley & Sons Inc.
Moyer, A. (1999). Ultimate attainment in L2 phonology: The critical factors of age, motivation, and instruction. Studies in second language acquisition, 21 (1), 81-108.
Gallagher, A., Bulteau, C., Cohen, D., & Michaud, J. L. (2019). Neurocognitive Development: Normative Development. Elsevier.
Olson, L. L., & Jay Samuels, S. (1973). The relationship between age and accuracy of foreign language pronunciation. The Journal of Educational Research, 66 (6), 263-268.
Penfield, W., & Roberts, L. (2014). Speech and brain mechanisms. Princeton University Press.
Piaget, J. (1962). The stages of the intellectual development of the child. Bulletin of the Menninger Clinic, 26 (3), 120.
Rosa, A. M., Silva, M. F., Ferreira, S., Murta, J., & Castelo-Branco, M. (2013). Plasticity in the human visual cortex: an ophthalmology-based perspective. BioMed research international, 2013.
Salkind, N. J. (Ed.). (2005). Encyclopedia of human development . Sage Publications.
Scott, J. P. (1962). Critical periods in behavioral development. Science, 138 (3544), 949-958.
Scovel, T. (1969). Foreign accents, language acquisition, and cerebral dominance 1. Language learning, 19 (3‐4), 245-253.
Scovel, T. (2000). A critical review of the critical period research. Annual review of applied linguistics, 20 , 213-223.
Skoe, E., & Kraus, N. (2013). Musical training heightens auditory brainstem function during sensitive periods in development. Frontiers in Psychology, 4, 622.
Slavoff, G. R., & Johnson, J. S. (1995). The effects of age on the rate of learning a second language. Studies in Second Language Acquisition, 17 (1), 1-16.
Snow, C. E., & Hoefnagel-Höhle, M. (1978). The critical period for language acquisition: Evidence from second language learning. Child development, 1114-1128.
Stockard, C. R. (1921). Developmental rate and structural expression: an experimental study of twins,‘double monsters’ and single deformities, and the interaction among embryonic organs during their origin and development. American Journal of Anatomy, 28 (2), 115-277.
White, E. J., Hutka, S. A., Williams, L. J., & Moreno, S. (2013). Learning, neural plasticity and sensitive periods: implications for language acquisition, music training and transfer across the lifespan. Frontiers in systems neuroscience, 7, 90.
Further Information
![Critical Period In Brain Development and Childhood Learning 2 Print Friendly, PDF & Email](https://www.simplypsychology.org/wp-content/uploads/three-icons-with-text-light-blue.jpg)
Breadcrumbs Section. Click here to navigate to respective pages.
![The Critical Period Hypothesis: Where Are We Now? The Critical Period Hypothesis: Where Are We Now?](https://images.tandf.co.uk/common/jackets/crclarge/978080581/9780805819519.jpg)
The Critical Period Hypothesis: Where Are We Now?
DOI link for The Critical Period Hypothesis: Where Are We Now?
Click here to navigate to parent product.
The idea that children have a special talent for languages that is rarely, if ever, available to older learners is one that has much popular support. Among second language researchers, however, the related hypothesis of a maturationally delimited critical period for language acquisition has been a constant source of controversy. Not everyone accepts the view that young children have an inborn advantage over older learners, and even among those who take this position, debate continues as to what the causes of this advantage are, what the relevant age limits are, what aspects of language development it applies to, and what sort of empirical data provide a crucial test of the critical period hypothesis. In this chapter, we review relevant research findings and consider various proposed explanations of age-related differences in (second) language acquisition. We argue that, despite a number of unresolved problems and even some apparent counterevidence, the critical period concept, as it has evolved, continues to have considerable heuristic value in investigating the language development of learners whose exposure to a new language begins at different ages.
- Privacy Policy
- Terms & Conditions
- Cookie Policy
- Taylor & Francis Online
- Taylor & Francis Group
- Students/Researchers
- Librarians/Institutions
Connect with us
Registered in England & Wales No. 3099067 5 Howick Place | London | SW1P 1WG © 2024 Informa UK Limited
Information
- Author Services
Initiatives
You are accessing a machine-readable page. In order to be human-readable, please install an RSS reader.
All articles published by MDPI are made immediately available worldwide under an open access license. No special permission is required to reuse all or part of the article published by MDPI, including figures and tables. For articles published under an open access Creative Common CC BY license, any part of the article may be reused without permission provided that the original article is clearly cited. For more information, please refer to https://www.mdpi.com/openaccess .
Feature papers represent the most advanced research with significant potential for high impact in the field. A Feature Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for future research directions and describes possible research applications.
Feature papers are submitted upon individual invitation or recommendation by the scientific editors and must receive positive feedback from the reviewers.
Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.
Original Submission Date Received: .
- Active Journals
- Find a Journal
- Proceedings Series
- For Authors
- For Reviewers
- For Editors
- For Librarians
- For Publishers
- For Societies
- For Conference Organizers
- Open Access Policy
- Institutional Open Access Program
- Special Issues Guidelines
- Editorial Process
- Research and Publication Ethics
- Article Processing Charges
- Testimonials
- Preprints.org
- SciProfiles
- Encyclopedia
![Languages languages-logo](https://pub.mdpi-res.com/img/journals/languages-logo.png?5e5753342ba82547)
Article Menu
![critical period hypothesis in language development critical period hypothesis in language development](https://pub.mdpi-res.com/bundles/mdpisciprofileslink/img/unknown-user.png?1723640743)
- Subscribe SciFeed
- Recommended Articles
- Google Scholar
- on Google Scholar
- Table of Contents
Find support for a specific problem in the support section of our website.
Please let us know what you think of our products and services.
Visit our dedicated information section to learn more about MDPI.
JSmol Viewer
The critical period hypothesis for l2 acquisition: an unfalsifiable embarrassment.
![critical period hypothesis in language development critical period hypothesis in language development](https://www.mdpi.com/bundles/mdpisciprofileslink/img/unknown-user.png)
1. Introduction
2. the notion of critical period, 3. cph or cphs, 4. problems with the “scrutinized nativelikeness” yardstick, 5. aptitude.
Although language-learning aptitude might seem to be a relatively stable individual characteristic when compared with other factors, such as motivational orientation and action control mechanisms, there seems to be some converging evidence that certain components of aptitude … might improve in the course of language learning.
6. Age or Opportunity?
7. looking for discontinuity, 8. neurolinguistics: new developments, 9. concluding remarks, author contributions, institutional review board statement, informed consent statement, data availability statement, conflicts of interest.
1 | ( ) defines critical periods as “a subset of sensitive periods for which the instructive influence of experience is essential for typical circuit performance and the effects of experience on performance are irreversible”, while a sensitive period occurs when “the effect of experience on the brain is particularly strong during a limited period in development”. However, the two terms are often used interchangeably. Moreover, in linguistics, there is a well-established tradition of referring to the sensitive/critical period for a second language as a “critical period”, even if it is closer to a sensitive period. We therefore follow ( ) in assuming these two terms to be interchangeable and not making a specific distinction between the two. |
- Abdel Aal, Alaa. 2016. Delayed puberty. Human Andrology 6: 27–30. [ Google Scholar ] [ CrossRef ]
- Abrahamsson, Niclas, and Kenneth Hyltenstam. 2008. The robustness of aptitude effects in near-native second language acquisition. Studies in Second Language Acquisition 30: 481–509. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Abrahamsson, Niclas, and Kenneth Hyltenstam. 2009. Age of onset and nativelikeness in a second language: Listener perception versus linguistic scrutiny. Language Learning 59: 249–306. [ Google Scholar ]
- Abrahamsson, Niclas. 2012. Age of onset and nativelike L2 ultimate attainment of morphosyntactic and phonetic intuition. Studies in Second Language Acquisition 34: 187–214. [ Google Scholar ] [ CrossRef ]
- Andringa, Sible. 2014. The use of native speaker norms in critical period hypothesis research. Studies in Second Language Acquisition 36: 565–96. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Asher, James, and Ramiro García. 1969. The optimal age to learn a foreign language. Modern Language Journal 53: 334–41. [ Google Scholar ]
- Ayer, Alfred J. 1959. History of the Logical Positivist movement. In Logical Positivism . Edited by Alfred J. Ayer. New York: Free Press, pp. 3–28. [ Google Scholar ]
- Bates, Elizabeth, Donna Thal, Doris Trauner, Judi Fenson, Dorothy Aram, Julie Eisele, and Ruth Nass. 1997. From first words to grammar in children with focal brain injury. Developmental Neuropsychology 13: 275–343. [ Google Scholar ] [ CrossRef ]
- Baumert, Jürgen, Johanna Fleckenstein, Michael Leucht, Olaf Köller, and Jens Möller. 2020. The long-term proficiency of early, middle, and late starters learning English as a foreign language at school: A narrative review and empirical study. Language Learning 70: 1091–135. [ Google Scholar ] [ CrossRef ]
- Bergmann, Christopher, Nienke Meulman, Laurie Stowe, Simone Sprenger, and Monika Schmid. 2015. Prolonged L2 immersion engenders little change in morphosyntactic processing of bilingual natives. Neuroreport 26: 1065–70. [ Google Scholar ] [ CrossRef ]
- Birdsong, David, and Jan Vanhove. 2016. Age of second-language acquisition: Critical periods and social concerns. In Bilingualism across the Lifespan: Factors Moderating Language Proficiency . Edited by Elena Nicoladis and Simona Montanari. Berlin and Washington: De Gruyter Mouton/American Psychological Association, pp. 163–82. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Birdsong, David. 2008. Second language acquisition and ultimate attainment. In The Handbook of Applied Linguistics . New York: Wiley, pp. 82–105. [ Google Scholar ]
- Birdsong, David. 2014. The Critical Period Hypothesis for second language acquisition: Tailoring the coat of many colors. In Essential Topics in Applied Linguistics and Multilingualism . Edited by Mirosław Pawlak and Larissa Aronin. Heidelberg: Springer, pp. 43–50. [ Google Scholar ]
- Birdsong, David. 2017. Critical periods. In Oxford Bibliographies in Linguistics . Edited by Mark Aronoff. New York: Oxford University Press, Available online: https://www.oxfordbibliographies.com/view/document/obo-9780199772810/obo-9780199772810-0139.xml (accessed on 10 August 2021).
- Birdsong, David. 2018. Plasticity, variability and age in second language acquisition and bilingualism. Frontiers in Psychology 9: 81. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Biro, Frank M., Bin Huang, Halley Wasserman, Catherine M. Gordon, and Susan M. Pinney. 2020. Pubertal growth, IGF-1, and windows of susceptibility: Puberty and future breast cancer risk. Journal of Adolescent Health 68: 517–22. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Bongaerts, Theo. 1999. Ultimate attainment in L2 pronunciation: The case of very advanced L2 learners. In Second Language Acquisition and the Critical Period Hypothesis . Edited by David Birdsong. Mahwah: Lawrence Erlbaum. [ Google Scholar ]
- Bongaerts, Theo. 2003. Effets de l’âge sur l’acquisition de la pronunciation d’une seconde langue. Acquisition et Interaction en Langue Étrangère 18: 79–98. [ Google Scholar ] [ CrossRef ]
- Bowden, Harriet Wood, Karsten Steinhauer, Cristina Sanz, and Michael T. Ullman. 2013. Native-like brain processing of syntax can be attained by university foreign language learners. Neuropsychologia 51: 2492–511. [ Google Scholar ] [ CrossRef ]
- Burstall, Clare. 1975. Primary French in the balance. Foreign Language Annals 10: 245–52. [ Google Scholar ] [ CrossRef ]
- Carroll, John B. 1975. The Teaching of French as a Foreign Language in Eight Countries . New York: Wiley. [ Google Scholar ]
- Carroll, John B. 1981. Twenty-five years of research on foreign language aptitude. In Individual Differences and Universals in Language Learning Aptitude . Edited by Karl C. Diller. Rowley: Newbury House, pp. 83–118. [ Google Scholar ]
- Chen, Tony, and Joshua K. Hartshorne. 2021. More evidence from over 1.1 million subjects that the critical period for syntax closes in late adolescence. Cognition 214: 104706. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Cisneros-Franco, J. Miguel, Patrice Voss, Maryse E. Thomas, and Etienne de Villers-Sidani. 2020. Critical periods of brain development. Handbook of Clinical Neurology 173: 75–88. [ Google Scholar ] [ CrossRef ]
- Clark, Herbert H., and Eve V. Clark. 1977. Psychology and Language: An Introduction to Psycholinguistics . New York: Harcourt Brace Jovanovich. [ Google Scholar ]
- Cook, Vivian. 2002. Background to the L2 user. In Portraits of the L2 User . Edited by Vivian Cook. Clevedon: Multilingual Matters, pp. 1–28. [ Google Scholar ]
- Cook, Vivian. 2016. Premises of multicompetence. In Cambridge Handbook of Linguistic Multi-Competence . Edited by Vivian Cook and Li Wei. Cambridge: Cambridge University Press, pp. 1–25. [ Google Scholar ]
- Dąbrowska, Ewa, Laura Becker, and Luca Miorelli. 2020. Is Adult Second Language Acquisition Defective? Frontiers in Psychology 11: 1839. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Dąbrowska, Ewa. 2012. Different speakers, different grammars: Individual differences in native language attainment. Linguistic Approaches to Bilingualism 2: 219–53. [ Google Scholar ] [ CrossRef ]
- Davies, Alan. 2003. The Native Speaker: Myth and Reality . Clevedon: Multilingual Matters. [ Google Scholar ]
- Davies, Alan. 2004. The native speaker in applied linguistics. In The Handbook of Applied Linguistics . Edited by Alan Davies and Catherine Elder. Malden: Blackwell, pp. 431–50. [ Google Scholar ]
- DeKeyser, Robert. 2000. The robustness of critical period effects in second language acquisition. Studies in Second Language Acquisition 22: 499–533. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- DeKeyser, Robert. 2003. Implicit and explicit learning. In Handbook of Second Language Acquisition . Edited by Catherine J. Doughty and Michael H. Long. London: Blackwell, pp. 313–48. [ Google Scholar ]
- DeLuca, Vincent, David Miller, Christos Pliatsikas, and Jason Rothman. 2019. Brain Adaptations and Neurological Indices of Processing in Adult Second Language Acquisition. In The Handbook of the Neuroscience of Multilingualism . New York: John Wiley & Sons, Ltd., pp. 170–96. [ Google Scholar ] [ CrossRef ]
- Dewaele, Jean-Marc, Thomas Bak, and Lourdes Ortega. In press. Why the mythical ‘native speaker’ has mud on its face. In Changing Face of the “Native Speaker”: Perspectives from Multilingualism and Globalization . Edited by Nikolay Slavkov, Sílvia Melo Pfeifer and Nadja Kerschhofer-Puhalo. Berlin: Mouton De Gruyter.
- Dollmann, Jörg, Irena Kogan, and Markus Weißmann. 2020. Speaking Accent-Free in L2 Beyond the Critical Period: The Compensatory Role of Individual Abilities and Opportunity Structures. Applied Linguistics 41: 787–809. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Eisenstein, Miriam. 1980. Childhood bilingualism and adult language learning aptitude. International Review of Applied Psychology 29: 159–74. [ Google Scholar ] [ CrossRef ]
- Ellis, Nick C. 2017. Chunking in language usage, learning and change: I don’t know. In The Changing English Language: Psycholinguistic Perspectives . Edited by Marianne Hundt, Sandra Mollin and Simone E. Pfenninger. Cambridge: Cambridge University Press, pp. 113–47. [ Google Scholar ]
- Flege, James E. 2019. A Non-critical Period for Second-language Learning. In A Sound Approach to Language Matters—In Honor of Ocke-Schwen Bohn . Edited by Anne Mette Nyvad, Michaela Hejná, Anders Højen, Anna Bothe Jespersen and Mette Hjortshøj Sørensen. Aarhus: Aarhus University, pp. 501–41. [ Google Scholar ]
- Flege, James Emil, and Ocke-Schwen Bohn. 2021. The Revised Speech Learning Model (SLM-r). In Second Language Speech Learning: Theoretical and Empirical Progress . Edited by Ratree Wayland. Cambridge: Cambridge University Press, pp. 3–83. [ Google Scholar ] [ CrossRef ]
- Flege, James Emil, Grace H. Yeni-Komshian, and Serena Liu. 1999. Age constraints on second-language acquisition. Journal of Memory and Language 41: 78–104. [ Google Scholar ] [ CrossRef ]
- Frank, Michael C. 2018. With Great Data Comes Great (Theoretical) Opportunity. Trends in Cognitive Sciences 22: 669–71. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Granena, Gisela, and Michael H. Long. 2013. Age of onset, length of residence, language aptitude, and ultimate L2 attainment in three linguistic domains. Second Language Research 29: 311–43. [ Google Scholar ] [ CrossRef ]
- Hartshorne, Joshua K., Joshua B. Tenenbaum, and Steven Pinker. 2018. A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition 177: 263–77. [ Google Scholar ] [ CrossRef ]
- Hoey, Michael. 2007. Grammatical creativity: A corpus perspective. In Text, Discourse and Corpora: Theory and Analysis . Edited by Michael Hoey, Michaela Mahlberg, Michael Stubbs and Wolfgang Teubert. London: Continuum, pp. 31–56. [ Google Scholar ]
- Huang, Becky H. 2016. A synthesis of empirical research on the linguistic outcomes of early foreign language instruction. International Journal of Multilingualism 13: 257–73. [ Google Scholar ] [ CrossRef ]
- Huang, Becky, Yung-Hsiang Shawn Chang, Luping Niu, and Mingxia Zhi. 2018. Examining the effects of socio-economic status and language input on adolescent English learners’ speech production outcomes. System 73: 27–36. [ Google Scholar ] [ CrossRef ]
- Hulstijn, Jan H. 2019. An individual-differences framework for comparing nonnative with native speakers: Perspectives from BLC theory. Language Learning 69: 157–83. [ Google Scholar ] [ CrossRef ]
- Huttenlocher, Janellen, Heidi Waterfall, Marina Vasilyeva, Jack Vevea, and Larry V. Hedges. 2010. Sources of variability in children’s language growth. Cognitive Psychology 61: 343–65. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Hyltenstam, Kenneth, and Niclas Abrahamsson. 2003. Maturational constraints in SLA. In The Handbook of Second Language Acquisition . Edited by Catherine Doughty and Michael H. Long. Malden: Blackwell, pp. 539–88. [ Google Scholar ]
- Hyltenstam, Kenneth. 1992. Non-native features of near-native speakers: On the ultimate attainment of childhood L2 learners. Advances in Psychology 83: 351–68. [ Google Scholar ]
- Jarvis, Scott, and Aneta Pavlenko. 2008. Crosslinguistic Influence in Language and Cognition . London: Routledge. [ Google Scholar ]
- Johnson, Jacqueline S., and Elissa L. Newport. 1989. Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology 21: 60–99. [ Google Scholar ] [ CrossRef ]
- Kasparian, Kristina, and Karsten Steinhauer. 2016. Confusing similar words: ERP correlates of lexical-semantic processing in first language attrition and late second language acquisition. Neuropsychologia 93: 200–17. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Kasparian, Kristina, and Karsten Steinhauer. 2017. When the Second Language Takes the Lead: Neurocognitive Processing Changes in the First Language of Adult Attriters. Frontiers in Psychology 8: 389. [ Google Scholar ] [ CrossRef ] [ PubMed ] [ Green Version ]
- Kinsella, Ciara, and David Singleton. 2014. Much more than age. Applied Linguistics 35: 441–62. [ Google Scholar ] [ CrossRef ]
- Knudsen, Eric. 2004. Sensitive periods in the development of the brain and behavior. Journal of Cognitive Neuroscience 16: 1412–25. [ Google Scholar ] [ CrossRef ]
- Kormos, Judit. 2013. New conceptualizations of language aptitude in second language attainment. In Sensitive Periods, Language Aptitude and Ultimate Attainment . Edited by Gisela Granena and Mike Long. Amsterdam: John Benjamins, pp. 131–52. [ Google Scholar ]
- Kral, Andrej, and Jos J. Eggermont. 2007. What’s to lose and what’s to learn: Development under auditory deprivation, cochlear implants and limits of cortical plasticity. Brain Research Reviews 56: 259–69. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Krashen, Stephen. 1973. Lateralization, language learning and the critical period: Some new evidence. Language Learning 23: 63–74. [ Google Scholar ] [ CrossRef ]
- Lantolf, James P., and Steven L. Thorne. 2006. Sociocultural Theory and the Genesis of Second Language Development . Oxford: Oxford University Press. [ Google Scholar ]
- Lenneberg, Eric H. 1967. Biological Foundations of Language . New York: Wiley. [ Google Scholar ]
- Long, Michael H. 1990. Maturational constraints on language development. Studies in Second Language Acquisition 12: 251–85. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Long, Michael H. 1993. Second language acquisition as a function of age. In Progression and Regression in Language: Sociocultural, Neuropsychological and Linguistic Perspectives . Edited by Kenneth Hyltenstam and Ake Viberg. Cambridge: Cambridge University Press, pp. 196–221. [ Google Scholar ]
- Long, Michael. 2013. Maturational constraints on child and adult SLA. In Sensitive Periods, Language Aptitude and Ultimate Attainment . Edited by Gisela Granena and Michael Long. Amsterdam: John Benjamins, pp. 3–41. [ Google Scholar ]
- Marinova-Todd, Stefka H., D. Bradford Marshall, and Catherine E. Snow. 2000. Three misconceptions about age and L2 learning. TESOL Quarterly 34: 9–34. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Meisel, Jürgen M. 2008. Child second language acquisition or successive first language acquisition? In Current Trends in Child Second Language Acquisition. A Generative Perspective . Edited by Belma Haznedar and Elena Gavruseva. Amsterdam: John Benjamins, pp. 55–80. [ Google Scholar ]
- Meisel, Jürgen M. 2010. Age of onset in successive acquisition of bilingualism: Effects on grammatical development. In Language Acquisition across Linguistic and Cognitive Systems . Edited by Michèle Kail and Maya Hickmann. Amsterdam: John Benjamins, pp. 225–48. [ Google Scholar ]
- Moyer, Alene. 1999. Ultimate attainment in L2 phonology: The critical factors of age, motivation and instruction. Studies in Second Language Acquisition 21: 81–108. [ Google Scholar ] [ CrossRef ]
- Moyer, Alene. 2004. Age, Accent and Experience in Second Language Acquisition. An Integrated Approach to Critical Period Inquiry . Clevedon: Multilingual Matters. [ Google Scholar ]
- Moyer, Alene. 2013. Foreign Accent. The Phenomenon of Non-Native Speech . Cambridge: Cambridge University Press. [ Google Scholar ]
- Moyer, Alene. 2014. What’s age got to do with it? Accounting for individual factors in second language accent. Studies in Second Language Learning and Teaching 4: 443–64. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Muñoz, Carmen, and David Singleton. 2011. A critical review of age-related research on L2 ultimate attainment’. Language Teaching 44: 1–35. [ Google Scholar ] [ CrossRef ]
- Murphy, Victoria A. 2014. Second Language Learning in the Early School Years: Trends and Contexts . Oxford: Oxford University Press. [ Google Scholar ]
- Nenert, Rodolphe, Jane B. Allendorfer, Amber M. Martin, Christi Banks, Jennifer Vannest, Scott K. Holland, and Jerzy P. Szaflarski. 2017. Age-related language lateralization assessed by fMRI: The effects of sex and handedness. Brain Research 1674: 20–35. [ Google Scholar ] [ CrossRef ]
- Nijakowska, Joanna. 2010. Dyslexia in the Foreign Language Classroom . Bristol: Multilingual Matters. [ Google Scholar ]
- Patkowski, Mark S. 1980. The sensitive period for the acquisition of syntax in a second language. Language Learning 30: 449–68. [ Google Scholar ] [ CrossRef ]
- Penfield, Wilder, and Lamar Roberts. 1959. Speech and Brain Mechanisms . Princeton: Princeton University Press. [ Google Scholar ]
- Pfenninger, Simone E., and David Singleton. 2017. Beyond Age Effects in Instructional L2 Learning: Revisiting the Age Factor . Bristol: Multilingual Matters. [ Google Scholar ]
- Piske, Thorsten, James Emil Flege, Ian R. A. MacKay, and Diane Meador. 2002. The production of English vowels by fluent early and late Italian-English bilinguals. Phonetica 59: 49–71. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Pliatsikas, Christos, Elisavet Moschopoulou, and James Douglas Saddy. 2015. The effects of bilingualism on the white matter structure of the brain. Proceedings of the National Academy of Sciences of the United States of America 112: 1334–37. [ Google Scholar ] [ CrossRef ] [ PubMed ] [ Green Version ]
- Popper, Karl. 1959. The Logic of Scientific Discovery . New York: Basic Books. [ Google Scholar ]
- Purves, Dale, George Augustine, David Fitzpatrick, Willliam C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and S. Mark Williams, eds. 2004. Neuroscience , 3rd ed. Sunderland: Sinauer. [ Google Scholar ]
- Roberts, Celia. 2013. Early puberty, ‘sexualization’ and feminism. European Journal of Women’s Studies 20: 138–54. [ Google Scholar ] [ CrossRef ]
- Robinson, Peter, ed. 2002. Individual Differences and Instructed Language Learning . Amsterdam: John Benjamins. [ Google Scholar ]
- Rosenthal, Judith W. 1996. Teaching Science to Language Minority Students: Theory and Practice . Clevedon: Multilingual Matters. [ Google Scholar ]
- Rossi, Eleonora, Judith F. Kroll, and Paola E. Dussias. 2014. Clitic pronouns reveal the time course of processing gender and number in a second language. Neuropsychologia 62: 11–25. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Rossi, Eleonora, Michele Diaz, Judith F. Kroll, and Paola E. Dussias. 2017. Late bilinguals are sensitive to unique aspects of second language processing: Evidence from clitic pronouns word-order. Frontiers in Psychology 8: 342. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Ruben, Robert J. 1997. A time frame of critical/sensitive periods of language development. Acta Otolaryngologica 117: 202–5. [ Google Scholar ] [ CrossRef ] [ PubMed ] [ Green Version ]
- Sáfár, Anna, and Judit Kormos. 2008. Revisiting problems with foreign language aptitude. International Review of Applied Linguistics in Language Teaching 46: 113–36. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Seliger, Herbert, Stephen Krashen, and Peter Ladefoged. 1975. Maturational constraints in the acquisition of second language accent. Language Sciences 36: 20–22. [ Google Scholar ]
- Sinclair, John. 1991. Corpus, Concordance, Collocation . Oxford: Oxford University Press. [ Google Scholar ]
- Singleton, David, and Justyna Leśniewska. 2021. Phraseology: Where lexicon and syntax conjoin. Research in Language and Education: An International Journal [RILE] 1: 46–58. [ Google Scholar ]
- Singleton, David, and Simone E. Pfenninger. 2016. Reporting on politically sensitive issues: The case of telling the truth about early L2 instruction. In Doing Real Research in Applied Linguistics . Edited by Jim McKinley and Heath Rose. London: Routledge, pp. 214–24. [ Google Scholar ]
- Singleton, David. 2005. The Critical Period Hypothesis: A coat of many colours. International Review of Applied Linguistics 43: 269–85. [ Google Scholar ] [ CrossRef ]
- Singleton, David. 2017. Language aptitude: Desirable trait or acquirable attribute? Studies in Second Language Learning and Teaching 7: 89–103. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Singleton, David. 2020a. Grammatical questions: Phraseological answers. In Text-Sentence-Word: Studies in English Linguistics, vol. IV . Edited by Agnieszka Uberman and Magdalena Trinder. Rzeszów: Wydawnictwo Uniwersytetu Rzeszowskiego. [ Google Scholar ]
- Singleton, David. 2020b. The translanguaging conundrum. In Bilingualism: Hungarian and Non-Hungarian Contexts . Edited by Szilvia Bátyi, Maria Gósy, Pal Heltai, Zsolt Lengyel and Szilard Szentgyörgy. Veszprém: Pannon Egyetem, pp. 175–84. [ Google Scholar ]
- Singleton, David. 2021. Postface. In Perspectives on the Second Language Phrasicon—The View from Learner Corpora . Edited by Sylviane Granger. Bristol: Multilingual Matters, pp. 235–44. [ Google Scholar ]
- Sparks, Richard L., Leonore Ganschow, Kay Fluharty, and Sherwin Little. 1995. An exploratory study on the effects of Latin on the native language skills and foreign language aptitude of students with and without learning disabilities. The Classical Journal 91: 165–84. [ Google Scholar ]
- Steinhauer, Karsten, and Kristina Kasparian. 2020. Brain plasticity in adulthood—ERP evidence for L1-attrition in lexicon and morphosyntax after predominant L2 use. Language Learning 70: 171–93. [ Google Scholar ] [ CrossRef ]
- Swain, Merrill, and Sharon Lapkin. 1989. Aspects of the sociolinguistic performance of early and late French immersion students. In Developing Communicative Competence in a Second Language . Edited by Robin C. Scarcella, Elaine S. Andersen and Stephen D. Krashen. Cambridge: Newbury House, pp. 41–54. [ Google Scholar ]
- Thorpe, William H. 1954. The process of song-learning in the chaffinch as studied by means of the sound spectrograph. Nature 173: 465–69. [ Google Scholar ] [ CrossRef ]
- Turnbull, Miles, Sharon Lapkin, Doug Hart, and Merrill Swain. 1998. Time on task and immersion graduates’ French proficiency. In French Second Language Education in Canada: Empirical Studies . Edited by Sharon Lapkin. Toronto: University of Toronto Press, pp. 31–55. [ Google Scholar ]
- Vanhove, Jan. 2013. The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis. PLoS ONE 8: e69172. [ Google Scholar ] [ CrossRef ] [ Green Version ]
- Vasilyeva, Marina, Heidi Waterfall, and Janellen Huttenlocher. 2008. Emergence of syntax: Commonalities and differences across children. Developmental Science 11: 84–97. [ Google Scholar ] [ CrossRef ] [ PubMed ]
- Wei, Li. 2018. Translanguaging as a practical theory of language. Applied Linguistics 39: 9–30. [ Google Scholar ] [ CrossRef ] [ Green Version ]
MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
Share and Cite
Singleton, D.; Leśniewska, J. The Critical Period Hypothesis for L2 Acquisition: An Unfalsifiable Embarrassment? Languages 2021 , 6 , 149. https://doi.org/10.3390/languages6030149
Singleton D, Leśniewska J. The Critical Period Hypothesis for L2 Acquisition: An Unfalsifiable Embarrassment? Languages . 2021; 6(3):149. https://doi.org/10.3390/languages6030149
Singleton, David, and Justyna Leśniewska. 2021. "The Critical Period Hypothesis for L2 Acquisition: An Unfalsifiable Embarrassment?" Languages 6, no. 3: 149. https://doi.org/10.3390/languages6030149
Article Metrics
Article access statistics, further information, mdpi initiatives, follow mdpi.
![MDPI Open Access Journals MDPI](https://pub.mdpi-res.com/img/design/mdpi-pub-logo-white-small.png?71d18e5f805839ab?1723640743)
Subscribe to receive issue release notifications and newsletters from MDPI journals
Suggestions or feedback?
MIT News | Massachusetts Institute of Technology
- Machine learning
- Sustainability
- Black holes
- Classes and programs
Departments
- Aeronautics and Astronautics
- Brain and Cognitive Sciences
- Architecture
- Political Science
- Mechanical Engineering
Centers, Labs, & Programs
- Abdul Latif Jameel Poverty Action Lab (J-PAL)
- Picower Institute for Learning and Memory
- Lincoln Laboratory
- School of Architecture + Planning
- School of Engineering
- School of Humanities, Arts, and Social Sciences
- Sloan School of Management
- School of Science
- MIT Schwarzman College of Computing
Cognitive scientists define critical period for learning language
Press contact :, media download.
![critical period hypothesis in language development critical period hypothesis in language development](https://news.mit.edu/sites/default/files/styles/news_article__download/public/download/201805/MIT-Language-Learning.jpg?itok=8yOyyRwQ)
*Terms of Use:
Images for download on the MIT News office website are made available to non-commercial entities, press and the general public under a Creative Commons Attribution Non-Commercial No Derivatives license . You may not alter the images provided, other than to crop them to size. A credit line must be used when reproducing images; if one is not provided below, credit the images to "MIT."
![critical period hypothesis in language development](https://news.mit.edu/sites/default/files/styles/news_article__image_gallery/public/images/201805/MIT-Language-Learning_0.jpg?itok=S5EAYlnf)
Previous image Next image
A great deal of evidence suggests that it is more difficult to learn a new language as an adult than as a child, which has led scientists to propose that there is a “critical period” for language learning. However, the length of this period and its underlying causes remain unknown.
A new study performed at MIT suggests that children remain very skilled at learning the grammar of a new language much longer than expected — up to the age of 17 or 18. However, the study also found that it is nearly impossible for people to achieve proficiency similar to that of a native speaker unless they start learning a language by the age of 10.
“If you want to have native-like knowledge of English grammar you should start by about 10 years old. We don’t see very much difference between people who start at birth and people who start at 10, but we start seeing a decline after that,” says Joshua Hartshorne, an assistant professor of psychology at Boston College, who conducted this study as a postdoc at MIT.
People who start learning a language between 10 and 18 will still learn quickly, but since they have a shorter window before their learning ability declines, they do not achieve the proficiency of native speakers, the researchers found. The findings are based on an analysis of a grammar quiz taken by nearly 670,000 people, which is by far the largest dataset that anyone has assembled for a study of language-learning ability.
“It’s been very difficult until now to get all the data you would need to answer this question of how long the critical period lasts,” says Josh Tenenbaum, an MIT professor of brain and cognitive sciences and an author of the paper. “This is one of those rare opportunities in science where we could work on a question that is very old, that many smart people have thought about and written about, and take a new perspective and see something that maybe other people haven’t.”
Steven Pinker, a professor of psychology at Harvard University, is also an author of the paper, which appears in the journal Cognition on May 1.
Quick learners
While it’s typical for children to pick up languages more easily than adults — a phenomenon often seen in families that immigrate to a new country — this trend has been difficult to study in a laboratory setting. Researchers who brought adults and children into a lab, taught them some new elements of language, and then tested them, found that adults were actually better at learning under those conditions. Such studies likely do not accurately replicate the process of long-term learning, Hartshorne says.
“Whatever it is that results in what we see in day-to-day life with adults having difficulty in fully acquiring the language, it happens over a really long timescale,” he says.
Following people as they learn a language over many years is difficult and time-consuming, so the researchers came up with a different approach. They decided to take snapshots of hundreds of thousands of people who were in different stages of learning English. By measuring the grammatical ability of many people of different ages, who started learning English at different points in their life, they could get enough data to come to some meaningful conclusions.
Hartshorne’s original estimate was that they needed at least half a million participants — unprecedented for this type of study. Faced with the challenge of attracting so many test subjects, he set out to create a grammar quiz that would be entertaining enough to go viral.
With the help of some MIT undergraduates, Hartshorne scoured scientific papers on language learning to discover the grammatical rules most likely to trip up a non-native speaker. He wrote questions that would reveal these errors, such as determining whether a sentence such as “Yesterday John wanted to won the race” is grammatically correct.
To entice more people to take the test, he also included questions that were not necessary for measuring language learning, but were designed to reveal which dialect of English the test-taker speaks. For example, an English speaker from Canada might find the sentence “I’m done dinner” correct, while most others would not.
Within hours after being posted on Facebook, the 10-minute quiz “ Which English? ” had gone viral.
“The next few weeks were spent keeping the website running, because the amount of traffic we were getting was just overwhelming,” Hartshorne says. “That’s how I knew the experiment was sufficiently fun.”
A long critical period
After taking the quiz, users were asked to reveal their current age and the age at which they began learning English, as well as other information about their language background. The researchers ended up with complete data for 669,498 people, and once they had this huge amount of data, they had to figure out how to analyze it.
“We had to tease apart how many years has someone been studying this language, when they started speaking it, and what kind of exposure have they been getting: Were they learning in a class or were they immigrants to an English-speaking country?” Hartshorne says.
The researchers developed and tested a variety of computational models to see which was most consistent with their results, and found that the best explanation for their data is that grammar-learning ability remains strong until age 17 or 18, at which point it drops. The findings suggest that the critical period for learning language is much longer than cognitive scientists had previously thought.
“It was surprising to us,” Hartshorne says. “The debate had been over whether it declines from birth, starts declining at 5 years old, or starts declining starting at puberty.”
The authors note that adults are still good at learning foreign languages, but they will not be able to reach the level of a native speaker if they begin learning as a teenager or as an adult.
"Although it has long been observed that learning a second language is easier early in life, this study provides the most compelling evidence to date that there is a specific time in life after which the ability to learn the grammar of a new language declines," says Mahesh Srinivasan, an assistant professor of psychology at the University of California at Berkeley, who was not involved in the study. “This is a major step forward for the field. The study also opens surprising, new questions, because it suggests that the critical period closes much later than previously thought."
Still unknown is what causes the critical period to end around age 18. The researchers suggest that cultural factors may play a role, but there may also be changes in brain plasticity that occur around that age.
“It’s possible that there’s a biological change. It’s also possible that it’s something social or cultural,” Tenenbaum says. “There’s roughly a period of being a minor that goes up to about age 17 or 18 in many societies. After that, you leave your home, maybe you work full time, or you become a specialized university student. All of those might impact your learning rate for any language.”
Hartshorne now plans to run some related studies in his lab at Boston College, including one that will compare native and non-native speakers of Spanish. He also plans to study whether individual aspects of grammar have different critical periods, and whether other elements of language skill such as accent have a shorter critical period.
The researchers also hope that other scientists will make use of their data, which they have posted online , for additional studies.
“There are lots of other things going on in this data that somebody could analyze,” Hartshorne says. “We do want to draw other scientists’ attention to the fact that the data is out there and they can use it.”
The research was funded by the National Institutes of Health and MIT’s Center for Minds, Brains, and Machines.
Share this news article on:
Press mentions, scientific american.
Bucking conventional wisdom, research co-authored by Prof. Josh Tenenbaum shows that “picking up the subtleties of grammar in a a second language does not fade until well into the teens,” writes Dana G. Smith for Scientific American . “To become completely fluent, however, learning should start before the age of 10.”
New research suggests “children are highly skilled at learning the grammar of a new language up until the age of 17 or 18, much longer than previously thought,” reports Kashmira Gander in Newsweek. “We may need to go back to the drawing board in trying to explain why adults have trouble learning language,” Joshua Hartshorne, who co-wrote the study as a postdoc at MIT, tells Gander.
A study co-authored by Prof. Josh Tenenbaum finds that learning a new language should start before age 10 to achieve a native-like grasp of the grammar, reports BBC News . People remain highly skilled language learners until about 17 or 18, but then fall off, which Tenenbaum says could be due to “a biological change” or “something social or cultural.”
Previous item Next item
Related Links
- Joshua Hartshorne
- Josh Tenenbaum
- Computational Cognitive Science Group
- Department of Brain and Cognitive Sciences
Related Topics
- Brain and cognitive sciences
- National Institutes of Health (NIH)
Related Articles
![critical period hypothesis in language development critical period hypothesis in language development](https://news.mit.edu/sites/default/files/styles/news_article__archive/public/images/201503/MIT-AgeCognition-02-update_0.jpg?itok=4Lwg4-wH)
The rise and fall of cognitive skills
![critical period hypothesis in language development critical period hypothesis in language development](https://news.mit.edu/sites/default/files/styles/news_article__archive/public/images/201711/MIT-Babies-Intuition.jpg?itok=Htuib_y3)
How badly do you want something? Babies can tell
![critical period hypothesis in language development critical period hypothesis in language development](https://news.mit.edu/sites/default/files/styles/news_article__archive/public/images/201710/MIT-Counterfact-1.jpg?itok=dryyxhoH)
How we determine who’s to blame
More mit news.
![critical period hypothesis in language development Screenshot of NeuroTrALE software shows hundreds of neuron filaments in red and one neuron highlighted in yellow.](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202408/neurotrale-neurons-00.png?itok=JGv_oViL)
New open-source tool helps to detangle the brain
Read full story →
![critical period hypothesis in language development A cartoon robot inspects a pile of wingdings with a magnifying glass, helping it think about how to piece together a jigsaw puzzle of a robot moving to different locations.](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202407/MIT-EmRep-LLMs.png?itok=JWWKbtVs)
LLMs develop their own understanding of reality as their language abilities improve
![critical period hypothesis in language development A diverse group of 6 people sit at a round table by a window](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202408/faculty-networking-luncheon.jpg?itok=jnoqd1HP)
Building bidirectional bridges
![critical period hypothesis in language development A diagram of the implantable device that releases naloxone](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202408/MIT_Overdose-Response-01-PRESS.jpg?itok=AONF74SY)
An implantable sensor could reverse opioid overdoses
![critical period hypothesis in language development Photo shows the rover’s long arm and the rocky brown Martian soil.](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202408/MIT-Mars-Organics-01-press.jpg?itok=yUZCdYG8)
Study: Rocks from Mars’ Jezero Crater, which likely predate life on Earth, contain signs of water
![critical period hypothesis in language development Photo of wind turbines in rural landscape, with neural-network graphic in the sky.](https://news.mit.edu/sites/default/files/styles/news_article__recent_news/public/images/202408/MIT-LLM-Anomaly-01-press.jpg?itok=DkayWsod)
MIT researchers use large language models to flag problems in complex systems
- More news on MIT News homepage →
Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA, USA
- Map (opens in new window)
- Events (opens in new window)
- People (opens in new window)
- Careers (opens in new window)
- Accessibility
- Social Media Hub
- MIT on Facebook
- MIT on YouTube
- MIT on Instagram
Warning: The NCBI web site requires JavaScript to function. more...
![critical period hypothesis in language development U.S. flag](https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.png)
An official website of the United States government
The .gov means it's official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.
The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.
- Publications
- Account settings
- Browse Titles
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001.
By agreement with the publisher, this book is accessible by the search feature, but cannot be browsed.
![critical period hypothesis in language development Cover of Neuroscience](https://www.ncbi.nlm.nih.gov/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-neurosci-lrg.png)
Neuroscience. 2nd edition.
The development of language: a critical period in humans.
Many animals communicate by means of sound, and some (humans and songbirds are examples) learn these vocalizations. There are, in fact, provocative similarities in the development of human language and birdsong ( Box B ). Most animal vocalizations, like alarm calls in mammals and birds, are innate, and require no experience to be correctly produced. For example, quails raised in isolation or deafened at birth so that they never hear conspecifics nonetheless produce the full repertoire of species -specific vocalizations. In contrast , humans obviously require extensive postnatal experience to produce and decode speech sounds that are the basis of language.
Importantly, this linguistic experience, to be effective, must occur in early life. The requirement for hearing and practicing during a critical period is apparent in studies of language acquisition in congenitally deaf children. Whereas most babies begin producing speechlike sounds at about 7 months (babbling), congenitally deaf infants show obvious deficits in their early vocalizations, and such individuals fail to develop language if not provided with an alternative form of symbolic expression (such as sign language; see Chapter 27). If, however, these deaf children are exposed to sign language at an early age (from approximately six months onward), they begin to “babble” with their hands just as a hearing infant babbles audibly. This suggests that, regardless of the modality , early experience shapes language behavior ( Figure 24.1 ). Children who have acquired speech but subsequently lose their hearing before puberty also suffer a substantial decline in spoken language, presumably because they are unable to hear themselves talk and thus lose the opportunity to refine their speech by auditory feedback.
Figure 24.1
Manual “babbling” in deaf infants raised by deaf, signing parents compared to manual babble in hearing infants. Babbling was judged by scoring hand positions and shapes that showed some resemblance to the components of American Sign Language. (more...)
Examples of pathological situations in which normal children were never exposed to a significant amount of language make much the same point. In one well-documented case, a girl was raised by deranged parents until the age of 13 under conditions of almost total language deprivation. Despite intense subsequent training, she never learned more than a rudimentary level of communication. This and other examples of so-called “feral children” starkly define the importance of early experience. In contrast to the devastating effects of deprivation on children, adults retain their ability to speak and comprehend language even if decades pass without exposure or speaking. In short, the normal acquisition of human speech is subject to a critical period : The process is sensitive to experience or deprivation during a restricted period of life (before puberty) and is refractory to similar experience or deprivations in adulthood.
On a more subtle level, the phonetic structure of the language an individual hears during early life shapes both the perception and production of speech. Many of the thousands of human languages and dialects use appreciably different repertoires of speech elements called phonemes to produce spoken words (examples are the phonemes “ba” and “pa” in English). Very young human infants can perceive and discriminate between differences in all human speech sounds, and are not innately biased towards the phonemes characteristic of any particular language. However, this universal appreciation does not persist. For example, adult Japanese speakers cannot reliably distinguish between the /r/ and /l/ sounds in English, presumably because this phonemic distinction is not present in Japanese. Nonetheless, 4-month-old Japanese infants can make this discrimination as reliably as 4-month-olds raised in English-speaking households (as indicated by increased suckling frequency or head turning in the presence of a novel stimulus). By 6 months of age, however, infants show preferences for phonemes in their native language over those in foreign languages, and by the end of their first year no longer respond to phonetic elements peculiar to non-native languages. The ability to perceive these phonemic contrasts evidently persists for several more years, as evidenced by the fact that children can learn to speak a second language without accent and with fluent grammar until about age 7 or 8. After this age, however, performance gradually declines no matter what the extent of practice or exposure ( Figure 24.2 ).
Figure 24.2
A critical period for learning language is shown by the decline in language ability (fluency) of non-native speakers of English as a function of their age upon arrival in the United States. The ability to score well on tests of English grammar and vocabulary (more...)
A number of changes in the developing brain could explain these observations. One possibility is that experience acts selectively to preserve the circuits in the brain that perceive phonemes and phonetic distinctions. The absence of exposure to non-native phonemes would then result in a gradual atrophy of the connections representing those sounds, accompanied by a declining ability to distinguish between them. In this formulation, circuits that are used are retained, whereas those that are unused get weaker (and eventually disappear). Alternatively, experience could promote the growth of rudimentary circuitry pertinent to the experienced sounds.
The reality, however, is considerably more complex than either of these scenarios suggest. Experiments by Patricia Kuhl and her colleagues have demonstrated that as a second language is acquired, the brain gradually groups sounds according to their similarity with phonemes in the native language. For example, when asked to categorize a continuous spectrum of artificial phonemes between /r/ and /l/, native English speakers, but not Japanese speakers, tend to perceive sounds as all sounding like either /r/ or /l/, a phenomenon that Kuhl has likened to a “perceptual magnet.” Related but varying sounds (defined by their audiographic spectrum) are evidently grouped together and eventually perceived as representing the same phoneme. Without ongoing experience during the critical period , this process fails to occur. Interestingly, the “baby-talk” or “parentese” used by adults speaking to young children actually emphasizes these phonetic distinctions compared to normal speech among adults. Thus, learning language during the critical period for its development entails an amplification and reshaping of innate biases by appropriate postnatal experience.
- Cite this Page Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. The Development of Language: A Critical Period in Humans.
- Disable Glossary Links
Related Items in Bookshelf
- All Textbooks
Related information
- PubMed Links to PubMed
Recent Activity
- The Development of Language: A Critical Period in Humans - Neuroscience The Development of Language: A Critical Period in Humans - Neuroscience
Your browsing activity is empty.
Activity recording is turned off.
Turn recording back on
Connect with NLM
National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894
Web Policies FOIA HHS Vulnerability Disclosure
Help Accessibility Careers
![critical period hypothesis in language development Language & Humanities](https://assets.languagehumanities.org/res/common/img/public/languagehumanities.org/logo.png)
- Linguistics
- Join Newsletter
Our Promise to you
Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy , ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.
Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.
What Is the Critical Period Hypothesis?
The critical period hypothesis is a theory in the study of language acquisition which posits that there is a critical period of time in which the human mind can most easily acquire language. This idea is often considered with regard to primary language acquisition, and those who agree with this hypothesis argue that language must be learned in the first few years of life or else the ability to acquire language is greatly hindered. The critical period hypothesis is also used in secondary language acquisition, regarding the idea of a time period in which a secondary language can be most easily acquired.
With regard to primary language acquisition, which refers to the process by which a person learns his or her first language , the critical period hypothesis is quite dramatic. This idea indicates that a person has only a set period of time in which he or she can learn a first language, usually the first three to ten years of development. During this time, language can be learned and acquired through exposure to language; simply hearing others talking on an ongoing and regular basis is sufficient. Once this time period is over, however, those who agree with the critical period hypothesis argue that primary language acquisition may be impossible or greatly impaired.
![critical period hypothesis in language development critical period hypothesis in language development](https://images.languagehumanities.org/slideshow-mobile-small/boy-child-in-red-shirt-crying.jpg)
There is a great deal of research into human brain development that supports this hypothesis, but it is still difficult to prove. One of the only conclusive ways to prove this hypothesis would be to have a person isolated from infancy until about the age of ten, without exposure to human speech. Such upbringing would be unthinkable, however, so this type of experiment cannot be conducted and the hypothesis remains largely unproven.
Unfortunate situations in which a child has been abused and isolated by his or her caregivers have provided opportunities to support the critical period hypothesis. In at least one instance, medical care and study of the child did demonstrate that full language acquisition was nearly impossible. Though this occurrence did support the hypothesis, secondary factors such as possible brain damage make the evidence flawed.
The critical period hypothesis is also frequently applied to secondary language acquisition, though in a somewhat less dramatic way. With regard to secondary language, many linguists and speech therapists agree that a second language can be acquired more easily when someone is young. Studies of the brain indicate that in youth the brain is still developing more quickly and new linguistic information can be processed and incorporated into the brain more easily. Once this period is over, however, secondary language acquisition is still certainly possible, though it can be more difficult.
- https://www.pbs.org/wgbh/nova/transcripts/2112gchild.html
Editors' Picks
![critical period hypothesis in language development What Is Travel Fiction?](https://images.languagehumanities.org/index-large/what-is-travel-fiction.webp)
Related Articles
- What Is Language Acquisition?
- What Is a Second Language?
- What Are the Different Types of Second Language Acquisition Theories?
![critical period hypothesis in language development What Is Knowledge Acquisition?](https://images.languagehumanities.org/index-large/knowledge-acquisition.jpg)
Our latest articles, guides, and more, delivered daily.
![](http://ortec.site/777/templates/cheerup1/res/banner1.gif)
COMMENTS
The critical period hypothesis [1] is a theory within the field of linguistics and second language acquisition that claims a person can only achieve native-like fluency [2] in a language before a certain age. It is the subject of a long-standing debate in linguistics [3] and language acquisition over the extent to which the ability to acquire language is biologically linked to developmental ...
Delineating the scope of the critical period hypothesis. First, the age span for a putative critical period for language acquisition has been delimited in different ways in the literature .Lenneberg's critical period stretched from two years of age to puberty (which he posits at about 14 years of age) , whereas other scholars have drawn the cutoff point at 12, 15, 16 or 18 years of age .
The critical period hypothesis of language development argues that children who fail to learn language before the end of childhood will not reach a 'native-like' level of mastery with the language, with full command of syntax, phonology and verbal working memory (Lenneberg, 1967). From: Neuroscience & Biobehavioral Reviews, 2013.
The 'critical period hypothesis' (CPH) is a particularly relevant case in point. This is the claim that there is, indeed, an optimal period for language acquisition, ending at puberty. However ... initial progress in acquiring the grammatical and lexical components of an L2 due to their higher level of cognitive development and greater ...
A critical period is a bounded maturational span during which experiential factors interact with biological mechanisms to determine neurocognitive and behavioral outcomes. In humans, the construct of critical period (CP) is commonly applied to first-language (L1) and second-language (L2) development. Some language researchers hold that during a ...
SUPPORT FOR THE CRITICAL PERIOD HYPOTHESIS. Hoping to extend Lenneberg's (1967) hypothesis to second language acquisition, early studies regarding the CPH aimed at establishing a link between the age of an individual's first exposure to a second language and his or her ultimate attainment in that language.
Critical Period and Language Development. The critical period hypothesis, as a long-standing debate in linguistics and language acquisition, briefly states that the ability to acquire language is biologically linked to chronological age. According to CPH, the first few years of life are the critical period for an individual to acquire language. ...
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
Proposed by Wilder Penfield and Lamar Roberts in 1959, the Critical Period Hypothesis (CPH) argues that there is a specific period of time in which people can learn a language without traces of the L1 (a so-called "foreign" accent or even L1 syntactical features) manifesting in L2 production (Scovel 48).
This has brought into question, in a similar vein to language development, whether there is actually a critical development period for infant-caregiver attachment. ... Second language acquisition and the critical period hypothesis, 133-159. Cisneros-Franco, J. M., Voss, P., Thomas, M. E., & de Villers-Sidani, E. (2020). Critical periods of ...
ABSTRACT. The idea that children have a special talent for languages that is rarely, if ever, available to older learners is one that has much popular support. Among second language researchers, however, the related hypothesis of a maturationally delimited critical period for language acquisition has been a constant source of controversy. Not ...
With regard to limits, as Bates et al. noted some years ago, "the end of the critical period for language in humans has proven… difficult to find, with estimates ranging from 1 year of age to adolescence" (p. 85). Differences concerning the offset of language-readiness go back to the origins of the Critical Period Hypothesis.
Delineating the scope of the critical period hypothesis. First, the age span for a putative critical period for language acquisition has been delimited in different ways in the literature .Lenneberg's critical period stretched from two years of age to puberty (which he posits at about 14 years of age) , whereas other scholars have drawn the cutoff point at 12, 15, 16 or 18 years of age .
Abstract. The present paper aims at highlighting the Critical Period Hypothesis (CPH) in Second Language Acquisition (SLA) which suggests that the individuals' attempts to learn a second ...
The findings suggest that the critical period for learning language is much longer than cognitive scientists had previously thought. "It was surprising to us," Hartshorne says. "The debate had been over whether it declines from birth, starts declining at 5 years old, or starts declining starting at puberty."
The Critical Period for Language Ac- quistion: Evidence from Second Language Learning. CHILD DEVELOPMENT, 1978, 49, 1114-1128. The critical period hypothesis holds that first language acquisition must occur before cerebral lateralization is complete, at about the age of puberty.
For example, the critical period for the development of a human child's binocular vision is thought to be between three and eight months, ... The hypothesis that language is acquired during a critical period was first proposed by neurologists Wilder Penfield and Lamar Roberts in 1959 and popularized by linguist Eric Lenneberg in 1967. Lenneberg ...
The first theory regarding critical period for language was suggested by Penfield andRoberts [5 ] later devel-oped by Lenneberg [6 ]. According to Lenneberg's ... ended may be too late to allow for normal language development. This crucial role of input can be seen studiesoftwopopulations:childrenwhogrewinisolation,
Importantly, this linguistic experience, to be effective, must occur in early life. The requirement for hearing and practicing during a critical period is apparent in studies of language acquisition in congenitally deaf children. Whereas most babies begin producing speechlike sounds at about 7 months (babbling), congenitally deaf infants show obvious deficits in their early vocalizations, and ...
Critical period hypothesis. The critical period hypothesis says that there is a period of growth in which full native competence is possible when acquiring a language. This period is from early childhood to adolescence. The critical period hypothesis has implications for teachers and learning programmes, but it is not universally accepted.
The critical period hypothesis for language development suggests that in order to learn a language fluently, people must start learning it before the age of nine. This theory is still being ...
The critical period hypothesis is a theory in the study of language acquisition which posits that there is a critical period of time in which the human mind can most easily acquire language. This idea is often considered with regard to primary language acquisition, and those who agree with this hypothesis argue that language must be learned in the first few years of life or else the ability to ...