research on language acquisition indicates that

Language Acquisition Theory

Henna Lemetyinen

Postdoctoral Researcher

BSc (Hons), Psychology, PhD, Developmental Psychology

Henna Lemetyinen is a postdoctoral research associate at the Greater Manchester Mental Health NHS Foundation Trust (GMMH).

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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.

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Language is a cognition that truly makes us human. Whereas other species do communicate with an innate ability to produce a limited number of meaningful vocalizations (e.g., bonobos) or even with partially learned systems (e.g., bird songs), there is no other species known to date that can express infinite ideas (sentences) with a limited set of symbols (speech sounds and words).

This ability is remarkable in itself. What makes it even more remarkable is that researchers are finding evidence for mastery of this complex skill in increasingly younger children.

Infants as young as 12 months are reported to have sensitivity to the grammar needed to understand causative sentences (who did what to whom; e.g., the bunny pushed the frog (Rowland & Noble, 2010).

After more than 60 years of research into child language development, the mechanism that enables children to segment syllables and words out of the strings of sounds they hear and to acquire grammar to understand and produce language is still quite an enigma.

Behaviorist Theory of Language Acquisition

One of the earliest scientific explanations of language acquisition was provided by Skinner (1957). As one of the pioneers of behaviorism , he accounted for language development using environmental influence, through imitation, reinforcement, and conditioning.

In this view, children learn words and grammar primarily by mimicking the speech they hear and receiving positive feedback for correct usage.

Skinner argued that children learn language based on behaviorist reinforcement principles by associating words with meanings. Correct utterances are positively reinforced when the child realizes the communicative value of words and phrases.

For example, when the child says ‘milk’ and the mother smiles and gives her some. As a result, the child will find this outcome rewarding, enhancing the child’s language development (Ambridge & Lieven, 2011).

Over time, through repetition and reinforcement, they refine their linguistic abilities. Critics argue this theory doesn’t fully explain the rapid pace of language acquisition nor the creation of novel sentences.

Chomsky Theory of Language Development

However, Skinner’s account was soon heavily criticized by Noam Chomsky, the world’s most famous linguist to date.

In the spirit of the cognitive revolution in the 1950s, Chomsky argued that children would never acquire the tools needed for processing an infinite number of sentences if the language acquisition mechanism was dependent on language input alone.

Noam Chomsky introduced the nativist theory of language development, emphasizing the role of innate structures and mechanisms in the human brain. Key points of Chomsky’s theory include:

Language Acquisition Device (LAD): Chomsky proposed that humans have an inborn biological capacity for language, often termed the LAD, which predisposes them to acquire language.

Universal Grammar: He suggested that all human languages share a deep structure rooted in a set of grammatical rules and categories. This “universal grammar” is understood intuitively by all humans.

Poverty of the Stimulus: Chomsky argued that the linguistic input received by young children is often insufficient (or “impoverished”) for them to learn the complexities of their native language solely through imitation or reinforcement. Yet, children rapidly and consistently master their native language, pointing to inherent cognitive structures.

Critical Period: Chomsky, along with other linguists, posited a critical period for language acquisition, during which the brain is particularly receptive to linguistic input, making language learning more efficient.

Critics of Chomsky’s theory argue that it’s too innatist and doesn’t give enough weight to social interaction and other factors in language acquisition.

Universal Grammar

Consequently, he proposed the theory of Universal Grammar: an idea of innate, biological grammatical categories, such as a noun category and a verb category, that facilitate the entire language development in children and overall language processing in adults.

Universal Grammar contains all the grammatical information needed to combine these categories, e.g., nouns and verbs, into phrases. The child’s task is just to learn the words of her language (Ambridge & Lieven).

For example, according to the Universal Grammar account, children instinctively know how to combine a noun (e.g., a boy) and a verb (to eat) into a meaningful, correct phrase (A boy eats).

This Chomskian (1965) approach to language acquisition has inspired hundreds of scholars to investigate the nature of these assumed grammatical categories, and the research is still ongoing.

Contemporary Research

A decade or two later, some psycho-linguists began to question the existence of Universal Grammar. They argued that categories like nouns and verbs are biologically, evolutionarily, and psychologically implausible and that the field called for an account that can explain the acquisition process without innate categories.

Researchers started to suggest that instead of having a language-specific mechanism for language processing, children might utilize general cognitive and learning principles.

Whereas researchers approaching the language acquisition problem from the perspective of Universal Grammar argue for early full productivity, i.e., early adult-like knowledge of the language, the opposing constructivist investigators argue for a more gradual developmental process. It is suggested that children are sensitive to patterns in language which enables the acquisition process.

An example of this gradual pattern learning is morphology acquisition. Morphemes are the smallest grammatical markers, or units, in language that alter words. In English, regular plurals are marked with an –s morpheme (e.g., dog+s).

Similarly, English third singular verb forms (she eat+s, a boy kick+s) are marked with the –s morpheme. Children are considered to acquire their first instances of third singular forms as entire phrasal chunks (Daddy kicks, a girl eats, a dog barks) without the ability to tease the finest grammatical components apart.

When the child hears a sufficient number of instances of a linguistic construction (i.e., the third singular verb form), she will detect patterns across the utterances she has heard. In this case, the repeated pattern is the –s marker in this particular verb form.

As a result of many repetitions and examples of the –s marker in different verbs, the child will acquire sophisticated knowledge that, in English, verbs must be marked with an –s morpheme in the third singular form (Ambridge & Lieven, 2011; Pine, Conti-Ramsden, Joseph, Lieven & Serratrice, 2008; Theakson & Lieven, 2005).

Approaching language acquisition from the perspective of general cognitive processing is an economic account of how children can learn their first language without an excessive biolinguistic mechanism.

However, finding a solid answer to the problem of language acquisition is far from being over. Our current understanding of the developmental process is still immature.

Investigators of Universal Grammar are still trying to convince that language is a task too demanding to acquire without specific innate equipment, whereas constructivist researchers are fiercely arguing for the importance of linguistic input.

The biggest questions, however, are yet unanswered. What is the exact process that transforms the child’s utterances into grammatically correct, adult-like speech? How much does the child need to be exposed to language to achieve the adult-like state?

What account can explain variation between languages and the language acquisition process in children acquiring very different languages to English? The mystery of language acquisition is granted to keep psychologists and linguists alike astonished decade after decade.

What is language acquisition?

Language acquisition refers to the process by which individuals learn and develop their native or second language.

It involves the acquisition of grammar, vocabulary, and communication skills through exposure, interaction, and cognitive development. This process typically occurs in childhood but can continue throughout life.

What is Skinner’s theory of language development?

Skinner’s theory of language development, also known as behaviorist theory, suggests that language is acquired through operant conditioning. According to Skinner, children learn language by imitating and being reinforced for correct responses.

He argued that language is a result of external stimuli and reinforcement, emphasizing the role of the environment in shaping linguistic behavior.

What is Chomsky’s theory of language acquisition?

Chomsky’s theory of language acquisition, known as Universal Grammar, posits that language is an innate capacity of humans.

According to Chomsky, children are born with a language acquisition device (LAD), a biological ability that enables them to acquire language rules and structures effortlessly.

He argues that there are universal grammar principles that guide language development across cultures and languages, suggesting that language acquisition is driven by innate linguistic knowledge rather than solely by environmental factors.

Ambridge, B., & Lieven, E.V.M. (2011). Language Acquisition: Contrasting theoretical approaches . Cambridge: Cambridge University Press.

Chomsky, N. (1965). Aspects of the Theory of Syntax . MIT Press.

Pine, J.M., Conti-Ramsden, G., Joseph, K.L., Lieven, E.V.M., & Serratrice, L. (2008). Tense over time: testing the Agreement/Tense Omission Model as an account of the pattern of tense-marking provision in early child English. Journal of Child Language , 35(1): 55-75.

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Early language acquisition: cracking the speech code

Patricia K. Kuhl 1

Nature Reviews Neuroscience volume 5 , pages 831–843 ( 2004 ) Cite this article

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Infants learn their native language quickly and effortlessly, and follow the same developmental path regardless of culture. However, it has proved difficult to understand how they do this, or to build computers that can reproduce this feat.

An early and essential task for infants is to make sense of the speech that they hear. Each language uses a unique set of about 40 phonemes, and infants must learn to partition varied speech sounds into these phonemic categories. Young infants are sensitive to subtle differences between all phonetic units, whereas older children lose their sensitivity to distinctions that are not used in their native language. The loss of discrimination for foreign-language distinctions is paralleled by an increase in sensitivity to native-language phonetic units.

There is evidence that infants analyse the statistical distributions of sounds that they hear in ambient language, and use this information to form phonemic categories. They also learn phonotactic rules — language-specific rules that govern the sequences of phonemes that can be used to compose words.

To identify word boundaries, infants can use both transitional probabilities between syllables, and prosodic cues, which relate to linguistic stress. Most languages are dominated by either trochaic words (with the stress on the first syllable) or iambic ones (with the stress on later syllables). Infants seem to use a combination of statistical and prosodic cues to segment words in speech.

Social influences are important in speech learning. Infants learn more easily from interactions with human beings speaking another language than they do from audiovisual exposure to the same language material, and their speech is strongly influenced by the response of others around them, such as their mothers. The importance of social input in language learning has some similarities to social influences on song learning in birds.

Language experience causes neural changes. One hypothesis, native language neural commitment (NLNC), proposes that language learning produces dedicated neural networks that code the patterns of native-language speech. As these networks develop, they make it easier for new speech elements and patterns to be learned if they are consistent with the existing patterns, but place constraints on the learning of foreign-language patterns. NLNC might explain the closing of the 'sensitive period' for language learning; once a certain amount of learning has occurred, neural commitment interferes with the learning of new languages so they cannot be learned as easily.

Infants learn language with remarkable speed, but how they do it remains a mystery. New data show that infants use computational strategies to detect the statistical and prosodic patterns in language input, and that this leads to the discovery of phonemes and words. Social interaction with another human being affects speech learning in a way that resembles communicative learning in songbirds. The brain's commitment to the statistical and prosodic patterns that are experienced early in life might help to explain the long-standing puzzle of why infants are better language learners than adults. Successful learning by infants, as well as constraints on that learning, are changing theories of language acquisition.

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research on language acquisition indicates that

How adults understand what young children say

Child-directed speech is optimized for syntax-free semantic inference

A systematic review and Bayesian meta-analysis of the acoustic features of infant-directed speech

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Acknowledgements

The author is supported by grants from the National institutes of Health, the Santa Fe Institute, the National Science Foundation (Science of Learning Center), and the William P. and Ruth Gerberding University Professorship Fund. The author thanks D. Padden, J. Pruitt, L. Yamamoto and T. Knight for assistance in preparing the manuscript, and A. Meltzoff and G. Cardillo for helpful comments on earlier drafts.

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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

Published: July 25, 2013
https://doi.org/10.1371/journal.pone.0069172
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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
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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.

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Front Psychol

A Review of Research on Technology-Supported Language Learning and 21st Century Skills

Associated data.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Modern society needs people to be equipped with 21st century skills (e.g., critical thinking, creativity, communication, digital literacy, or collaboration skills). For this reason, teaching and learning nowadays should promote not only students' knowledge acquisition in various learning contexts but also their 21st century skills, and language learning context is no exception. This study reviewed research on technology-supported language learning and 21st century skills. The reason is that earlier studies reviewed only articles related to language learning supported by technology and mostly focused on languages, language skills and technologies used. That is to say, 21st century skills were not considered in earlier review studies. The present study selected and reviewed 34 articles published between 2011 and 2022 (February) and focused on the following dimensions: (1) research focus such as language skills and 21st century skills; (2) theoretical foundations; (3) technologies; (4) learning activities; (5) methodology; and (6) findings. The present research found that reviewed studies had focused most frequently on such language skills as speaking and writing and on such 21st century skills as communication and collaboration. The social constructivism theory was often used by scholars to base their studies on. Facebook, Google Docs, and Moodle were popular technologies in reviewed studies to facilitate language and 21st century skills. Scholars in reviewed studies reported that technology-supported language learning activities provided learners with good learning experiences and enhanced their learning motivation, engagement, and confidence. However, some challenges that learners faced during learning activities were also reported. Based on the results of the review, this study made several recommendations for stakeholders such as educators and researchers in the field.

Introduction

It is important that our students not only acquire new knowledge when they learn, but also develop skills, such as problem-solving, social cooperation, creativity, and so on, in order to apply newly learned knowledge to the real world. Such knowledge and skills will help them adapt to modern society and will enhance their competitiveness (Shadiev et al., 2022a , b ). Many countries have put forward the 21st century skills framework to carry out education reform (Lin et al., 2020 ), and one of them was proposed by the Partnership for 21st Century (P21). The P21 (Partnership for 21st Century Skills, 2008 ) provided a detailed conceptual framework and listed three types of skills: (1) learning and innovation skills (critical thinking and problem solving, creativity and innovation, and communication and collaboration), (2) digital literacy (information literacy, media literacy, and information and communication technologies (ICT) literacy), and (3) career and life skills (flexibility and adaptability, initiative and self-direction, social and cross-cultural interaction, productivity and accountability, and leadership and responsibility). The essence of these skills is that they are key skills that learners will need for their social and professional life in the future. These skills also emphasize the ability of learners to use and transfer knowledge and solve problems in complex situations, so they can achieve deep levels of individual learning as well as lifelong learning (Shadiev et al., 2022a ).

Developing students' 21st century skills needs to be implemented in all disciplines, and foreign language learning is no exception (Shadiev et al., In Press ). This matter has been addressed in the documents related to Asia Pacific Economic Cooperation ( 2004 ). Furthermore, researchers have carried out related studies, and pointed out the advantages of technology in developing both language skills and 21st century skills (Shadiev et al., In Press ). For example, Suzanne ( 2014 ) pointed out that when developing learners' reading skills, they deepened the learners' understanding of reading content, and also developed critical thinking skills. García-Sánchez and Burbules ( 2016 ) have found that students' skills such as problem solving, collaboration, listening and speaking improved after they completed online collaborative tasks. Srebnaja and Stavicka ( 2018 ) also pointed out that, in language learning projects supported by WebQuest, students' creativity, collaboration, and speaking skills have been developed. In the study by Chiang ( 2020 ), the digital storytelling activity was designed which promoted language learners' writing skills as well as their digital literacy skills.

A theoretical foundation to support technology supported language learning and development of 21st century skills can be built on various theories. The most relevant can be considered as second language acquisition theory, socio-cultural theory, and constructivism theory. For example, second language acquisition theory states that language acquisition is a process of input, absorption, and output. Language acquisition is acquired through exposure to contexts, understanding discourse, and then using language in natural communicative contexts (Krashen, 1985 ). According to socio-cultural theory, learning is a social phenomenon; it emphasizes the social nature of learning and argues that the development of learners' abilities arises from interpersonal interactions (Lantolf, 2000 ). Constructivism theory suggests that learning is a process in which a learner actively constructs meaning. That is, learners generate meaning and construct understanding based on prior knowledge and experience, often in the context of socio-cultural interactions. Constructivism theory emphasizes the social and contextual nature of learning (Vygotsky, 1978 ). Over the years, scholars have created technology-supported learning environments for language learning and 21st century skills development based on these theories. Such environments provide students with authentic learning materials, support social interaction, and facilitate their creative expression and construction of meaning actively using the target language.

Some related review studies already exist in the field. For example, Shadiev and Yang ( 2020 ) reviewed 398 articles related to technology-assisted language learning published in 10 Social Science Citation Index (SSCI) journals. The dimensions analyzed in their study included target language, language skills, technologies, and research findings. Shadiev and Yang ( 2020 ) found that the most commonly used language was English, followed by Chinese. The most targeted language skills were writing, speaking, and vocabulary acquisition. Digital games and online videos were the most commonly used technologies in these reviewed studies. In addition, most of the reviewed studies reported positive impacts of technology applications on language learning. Zhang and Zou ( 2020 ) reviewed 57 articles on technology applications for language learning that were published between 2016 and 2019 in 10 SSCI journals. The types of technology, the purpose of technology use, and the effectiveness of the technologies were reviewed by the authors. Zhang and Zou ( 2020 ) found that mobile learning, multimedia learning and socialization, voice to text recognition, text to speech recognition, and digital game-based learning were the most frequently investigated types of technology in the literature. The purposes for their use mainly covered four areas, including promoting practice, providing teaching content, promoting interaction, and reconstructing teaching methods. Scholars have claimed that technologies have positive effects on language learning. Goksu et al. ( 2020 ) reviewed 310 articles in 10 journals in the field of technology-assisted language learning. In addition, they evaluated a metadata set of 469 articles in the Web of Science database through bibliometric mapping. The review focused on the types, purposes, and effectiveness of the latest technologies on language learning. Goksu et al. ( 2020 ) found that most studies used quantitative research methods and were carried out with participants at higher academic levels. In addition, most studies focused on language skills as well as learning motivation and learner perceptions. Shadiev et al. ( 2017 ) studied 37 articles published in the top 10 SSCI journals related to educational technology from 2007 to 2016 (March). Scholars took mobile language learning in a real environment as the research object and summarized the results from four perspectives: journal publishing trends, language learning, research focus, and research methods. The results showed that the journal publishing trend was increasing. The most common research focus was cognition and language learner proficiency. The results also showed that mobile technology was positively perceived and accepted by students in most of these studies, and the technology was also found to have a positive impact on the students' language skills.

By exploring these review studies, the present review research found that 21st century skills were not considered in these earlier studies at all because scholars mainly focused on language skills. Therefore, several important aspects (e.g., theoretical foundations used to support the studies, methodology, and types of learning activities that promote language skills and 21st century skills) were ignored. These aspects are important for stakeholders in the design and implementation of language teaching and learning for 21st century skills development. In order to fill this gap in the literature, the present study was carried out, and the following research questions were addressed:

What language skills and 21st century skills did the researchers focus on in the reviewed studies?
What theories were used as a foundation in reviewed studies?
What technologies were used to promote language skills and 21st century skills?
What learning activities were used in the reviewed studies?
What were the methodological characteristics of the reviewed studies?
What research findings were obtained in the reviewed studies?

Research Method

The present study is a systematic review. The study used preferred reporting items for systematic reviews and meta-analyses (PRISMA) for the electronic search. PRISMA is considered as a set of programs that facilitates researchers to prepare and report various systematic evaluations and meta-analyses (Moher et al., 2009 ). According to scholars, PRISMA has been widely and successfully applied in educational research. In addition to PRISMA, this review followed the general guidelines for searching and selecting research articles proposed by Avgousti ( 2018 ), Shadiev and Yang ( 2020 ), and Shadiev and Yu ( In Press ). The search and selection processes are shown in Figure 1 . Articles were found through a search on the Web of Science database and Peer-Reviewed Instructional Materials Online Database (PRIMO). According to Kukulska-Hulme and Viberg ( 2018 ), PRIMO is a search tool and it contains several databases such as ERIC and Scopus. For this reason, PRIMO features a very comprehensive collection of full-text articles and bibliographic records, and it has been used by many researchers in their systematic reviews and meta-analyses to find relevant literature.

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The search and selection process.

Based on general recommendations from previous review studies (Guan, 2014 ; Duman et al., 2015 ), this review used keywords such as 21st century skills, language learn * , and technology. 21st century skills were also included to widen the search results (e.g., creativity and innovation, critical thinking, problem solving, communication, collaboration, digital literacy, information literacy, media literacy, ICT literacy, flexibility and adaptability, initiative and self-direction, social and cross-cultural interaction, productivity and accountability, leadership and responsibility). This review used these terms in different combinations to search articles.

A total of 9,162 articles were found from the search. This review narrowed down the selection of research articles based on the following criteria (see Figure 1 ): articles that were (1) published during 2011–2022 (February); (2) published in English; and (3) focused on technology-supported language learning and 21st century skills. Two researchers screened each article individually and excluded articles from the study that did not focus on technology-supported language learning and 21st century skills. The researchers discussed any discrepancies in their selection results until an agreement was reached. At the end of the selection process, 34 empirical studies were chosen for the review.

This review proposed an analytical framework (see Figure 2 ) to answer the research questions of the study and to better understand the research design of the reviewed studies and findings. This review also used this framework to help us better review articles and regarded it as the basis for coding the content of reviewed studies. This review used the open coding method to carry out content analysis (Creswell, 2002 ) which can enable us to segment research content and to form categories relevant to the phenomenon of interest. The analytical dimensions included the following (see Figure 2 ): (1) language skills and 21st century skills—skills related to language learning and 21st century skills, (2) technology—the tools and devices participants used for language learning, (3) learning activities supported by technology to cultivate 21st century skills and language skills, (4) theoretical foundation—theories, models or hypothesis involved in research, (5) methodology—participants' academic level and major, research duration, sample size, data collection tools, and research design, and (6) findings—results reported in research.

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Analytical framework.

Two researchers were involved in the coding process. They read articles and coded content according to the above coding scheme. After that, they categorized codes into categories and identified attributes for each category. If there were any differences in coding, the researchers re-examined an article to resolve differences, and then finally completed the coding phase. Interrater reliability was measured using Cohen's kappa coefficient and the result was high (k = 0.886).

The present study starts this section with the results related to publication year, languages, and participants. Figure 3 shows the distribution of articles published in the past 10 years. Most studies were published in 2019 ( n = 8), and no articles were published in 2012. From the figure, it can also be seen that the research trend in this field is on the rise. Figure 4 demonstrates the frequency at which different languages were the focus in the reviewed studies. 29 studies focused on English. There were also studies focused on Chinese ( n = 2), Ukrainian ( n = 1), Japanese ( n = 1), and Spanish ( n = 1). As shown in Figure 5 , undergraduates were the most common academic level ( n = 17), and there was a relatively low number of studies conducted on junior high school ( n = 5), senior high school ( n = 2), and primary school ( n = 1) academic levels. As shown in Figure 6 , researchers were more willing to involve students who were majoring in the fields of education ( n = 9), management ( n = 4), or engineering ( n = 4).

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Distribution of research year.

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Distribution of languages.

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Distribution of educational level.

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Distribution of participants' major.

Research Focus

This section presents the results related to research focus of reviewed articles. As can be seen from Figure 7 (and from Appendix 1 ), researchers carried out technology-assisted language learning studies and focused on the development of listening, speaking, reading, writing, grammar, and vocabulary skills. Among these skills, speaking skills ( n = 20) received considerable attention from researchers, followed by writing skills ( n = 19) and vocabulary ( n = 13). Reading ( n = 5) skills received less interest from researchers.

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Distribution of language skills.

According to Figure 8 (and Appendix 1 ), researchers pointed out that technology-supported language learning can also promote 21st century skills. These skills relate to the following three categories: 4C (communication, collaboration, critical thinking, and creativity), digital literacy, and career and life skills. The most common skills that scholars targeted were communication ( n = 15) and collaboration ( n = 15), followed by critical thinking ( n = 10) and social and cross-cultural interaction ( n = 10). Problem solving ( n = 5) skills have received the least attention from researchers.

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Distribution of 21st century skills.

Theoretical Foundation

This section focuses on theoretical foundation in the reviewed articles. As shown in Appendix 2 , a total of 16 theories were used. The most used theory was the social constructivism theory ( n = 9), followed by Byram's intercultural competence model ( n = 3), project-based learning ( n = 2), content based instruction ( n = 2), task based approach to language teaching ( n = 2), and sociocultural theory ( n = 2). The rest of theories were used only once.

As shown in Appendix 3 , a total of 52 technologies were used in reviewed studies. This review grouped them into eight categories: Social tools ( n = 20), Creative tools ( n = 19), Collaboration tools ( n = 13), Learning management system ( n = 9), Multimedia materials ( n = 5), Classroom interactive tools ( n = 4), Presentation tools ( n = 2), Wearable devices ( n = 1). Among the most commonly used technologies were Facebook ( n = 4), Google Docs ( n = 4), Moodle ( n = 4), followed sequentially by Skype ( n = 3), Padlet ( n = 3), WhatsApp ( n = 2), YouTube ( n = 2), Blogs ( n = 2), Google Drive ( n = 2), and Wiki ( n = 2). The other 40 technologies have only been used once, i.e., Windows Movie Maker, Live On, Edmodo, Kahoot, and Prezi. In addition, one study involved a virtual reality production tool (EduVenture) and a wearable device (Google Cardboard).

Learning Activity

As shown in Appendix 4 , in reviewed studies, scholars designed the following five main types of learning activities: (1) collaborative task-based language learning ( n = 9); (2) learning activities based on online communication ( n = 9); (3) creative work-based language learning ( n = 8); (4) adaptive learning activities ( n = 4); and (5) learning activities based on multimedia materials ( n = 4).

Methodology

This section presents methodological details of reviewed studies, such as sample size, research duration, data collection tools and research design.

As shown in Figure 9 , the most common sample size was from 11 to 30 participants ( n = 11), followed by sample sizes between 61 and 90 ( n = 8) and between 31 and 7 ( n = 7). Only two studies selected a sample size between 1 and 10. The sample size of two studies was >151. As shown in Figure 10 , most of research duration was between 3 and 6 months ( n = 10). There were 12 studies that did not state any research duration.

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Sample size distribution.

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Research duration distribution.

As shown in Appendix 5 , the most common data collection method was questionnaires ( n = 17), followed by tests ( n = 15) and interviews ( n = 13). Two data collection methods were used only 2 times, they were scales ( n = 2) and rubric ( n = 2).

As shown in Appendix 6 , research designs related to technology-supported language learning and 21st century skills were categorized into three main categories, namely quasi-experimental research ( n = 14), case studies ( n = 12), and action research ( n = 8).

As shown in Appendix 7 , various findings were reported in reviewed studies. In addition, that learners' language skills acquisition and 21st century skills, technology-supported language learning activities provided learners with good learning experiences, enhanced motivation and engagement, and improved self-confidence. In reviewed studies, some scholars reported about challenges faced by students during learning activities; they included challenges from technology, from their own competence, challenges of collaborating with others and self-attitude.

Language Skills

Regarding language skills, researchers have focused on improving learners' speaking, writing and vocabulary skills more. This shows that researchers are more concerned with the improvement of learners' skills related to language output. Researchers who reviewed studies on technology-supported language learning from 2014 to 2019 came to the same conclusion (Shadiev and Yang, 2020 ). However, the present study showed that reading skills received the least attention, while previous studies noted that grammar skills received less attention. This revealed that researchers are now beginning to pay more attention to previously neglected skills and are beginning to focus on the role of technology-supported language learning in facilitating learners' grammar skills. For example, Lai ( 2017 ) noted that grammar skills improved when learners completed activities to create vocabulary lists and greeting cards using multimedia resources. Jung et al. ( 2019 ) noted that students' grammar skills improved as they corrected each other's pronunciation and grammatical errors through video chat. Jamalai and Krish ( 2021 ) found that students' grammar skills improved through online forum discussions and knowledge sharing.

21st Century Skills

In terms of 21st century skills, communication and collaboration have received the most attention from researchers. It is probably because the 21st century society is more globalized and along with the increased complexity of related work, interpersonal communication and cooperation are being enhanced. The 21st century society emphasizes teamwork skills, and therefore scholars focus on collaborative and communication skills. Problem-solving skills have received little attention, and no researcher focused on career and life skills. In the face of the evolving and changing society of the future, problem-solving skills are among the core 21st century skills, emphasizing learners' ability to define problems, think critically, and solve problems. For example, scholars in reviewed studies have focused on learners' problem-solving skills in virtual technology-supported language learning (Chen et al., 2021 ).

Based on the results, this study has several recommendations for educators and researchers. First, input skills are an important component of language skills and an indispensable way for learners to develop output skills (Harmer, 2007 ). The present study suggests that researchers can focus on learners' input skills supported by technology, such as listening and reading. Second, problem-solving skills and career and life skills also deserve attention; therefore, future studies try to explore the effects of technology-supported language learning on these skills.

Theories Related to Instructional Design

The most commonly used instructional design theory in reviewed studies was social constructivism theory. The results of this research are consistent with those of previous review studies of technology-supported language learning (Parmaxi and Zaphiris, 2017 ). According to this theory (Vygotsky, 1978 ), knowledge is not a set of “facts” but rather a synthesis of information that is actively constructed and evolving in the learner's mind. The teacher does not “give” knowledge to the learner, but the learner should acquire knowledge actively. Learners' knowledge evolves as they process old and new information, as well as their experiences. The researchers designed collaborative, creative, and communicative activities based on a social constructivism perspective to encourage learners to input the target language and output the target language in a meaningful context. At the same time, researchers have used various learning and teaching activities to promote students' collaboration, communication, creativity, critical thinking and digital literacy skills (Yang et al., 2013 , 2014 , 2022 ; Lai, 2017 ; Sevilla-Pavón and Nicolaou, 2017 ; Huang, 2021 ).

Other researchers have also used theories based on learner-centered pedagogies such as problem-based or project-based theories. These pedagogies are all used to promote student-directed learning, adaptive learning, and personalized assessment. Learning theories were used to design activities that provided learners with opportunities for language input and output, e.g., to learn new knowledge and then apply it to the real world by creating own content. This allows learners to acquire language skills and develop 21st century skills such as communication, collaboration, and problem solving (Arnó-Macià and Rueda-Ramos, 2011 ; Yang et al., 2013 , 2014 ; Srebnaja and Stavicka, 2018 ).

Theories Related to Language Learning

Researchers have also designed learning activities based on theories related to foreign language learning, such as task-based language teaching, content-based instruction, and output-input theory. For example, digital story creation activities and integrated cross-cultural communication activities designed by the researcher are in line with these theoretical perspectives, in which learners have access to the target language through social tools and partner communication. The ability to use creative and collaborative tools to complete target-language based tasks also contributes to the acquisition of language skills and 21st century skills development, such as social and cross-cultural interaction, communication skills (Lewis and Schneider, 2015 ; Tseng, 2017 ).

Theories Related to Measuring Learning Outcomes

Since language learning is closely related to culture, scholars have designed foreign language courses based on cross-cultural communication, where learners acquired both language skills and cultural knowledge. Further, there are theories that have been used by scholars to assess and measure learners' outcomes. For example, researchers have focused on learners' intercultural competence along with their language skills and utilized the Byram' ICC model and the developmental model of intercultural sensitivity to measure their cross-cultural knowledge acquisition and skills development (Bennett, 1986 ; Byram, 1997 ). In addition, the Keller' ARCS motivational model (Keller, 1987 ) has been used by researchers to measure learners' perceived attention, relevance, confidence, and satisfaction in technology-supported language learning environments.

This review analyzed the theoretical foundation that was used by those few studies that focused on non-English languages such as Chinese, Ukrainian, Japanese, and Spanish. This review found that learning theories used by scholars in these studies were diverse. They were related to instructional design (e.g., social constructivism), language learning (e.g., language output and input), and cross-cultural learning (e.g., intercultural sensitivity).

Based on the findings, several suggestions for educators and researchers are proposed. First, the theories mentioned by researchers are instruction-related theories, language learning-related theories, and measurement-related theories; they were used to guide the design of technology-supported language learning activities that focus both on the acquisition of language skills and on the 21st century skills. These theories can be useful to inform the design of appropriate language learning activities for educators and researchers in the future. Second, this review found that many researchers did not indicate what theories were used in their studies. Theoretical foundations are important for the instructional design, language learning or measuring activities, so such information should be clearly indicated so that other researchers can gain a deeper understanding of them.

Eight Technologies With Different Functions

Based on the literature review, this study grouped technologies into eight categories based on their functions: (1) collaborative tools (e.g., Google Docs or Padlet) for supporting learners to collaborate on a task through co-editing and information sharing; (2) social tools (e.g., Facebook or Skype) for supporting learners to communicate and share content remotely or synchronously using text, audio and video; (3) creative tools (e.g., Photo Story or Adobe Spark) to support learners in creating work, such as digital stories or videos; (4) learning management system (e.g., Moodle) to integrate learning activities and learning resources for adaptive online learning; (5) classroom interaction tools (e.g., Quizlet or Kahoot) to support question-answering, polling, and other activities in the classroom; (6) multimedia materials are some audio and video resources on the web or multimedia textbooks; (7) presentation tools (e.g., PowerPoint) are used to support learners to present their learning content digitally; (8) wearable devices (e.g., Google Glass) to support learners to view or interact with content in virtual reality learning environments.

Most Commonly Used Technologies

Facebook (social tool), Google Docs (collaboration tool), and Moodle technologies (learning management system) were used the most in previous studies to facilitate language and 21st century skills. The study further analyzed which technologies are most often used by researchers to promote 21st century skills. Appendix 8 demonstrates these most commonly used tools. The study found that Facebook (social tool), Google Docs (collaboration tool) and Moodle (learning management system) were also the tools most often used by researchers to promote communication, collaboration and critical thinking, social and cross-cultural interaction skills. This indicates that scholars valued such 21st century skills as collaboration and communication among students in technology-supported language learning activities. For example, Sevy-Biloon and Chroman ( 2019 ) used social and collaborative tools (e.g., Google Docs, Facebook, etc.) to support communication between students from different cultural backgrounds and their results showed that students' speaking skills, social and cross-cultural interaction, and communication skills were promoted. Moodle is popular among researchers because this learning management system not only supports learners' adaptive and inquiry-based learning, but also helps teachers share learning resources with learners, design learning activities, and manage learners' learning progress (García-Sánchez and Burbules, 2016 ). For example, Yang et al. ( 2014 ) designed a language learning activity based on the Moodle platform that asked students to complete reading and writing tasks in the system to promote the development of reading, writing skills and critical thinking. In addition, researchers most often used Google Docs (collaboration tool), Prezi (presentation tool), Windows Movie Maker, Photo Story3 (creative tools) and Blogs (social tool) to support students' creativity and innovation skills, problem-solving skills, and ICT literacy. And only two studies have used films (multimedia materials) and blogs (social tool) to support students' media literacy.

Experienced Challenges of Using Technology

Scholars reported that technologies pose some challenges for learners. For example, students were not experienced to use technology and had no trainings before learning activities; then they complained about problems to use technology during learning (Lai, 2017 ). Students were also confused about the layout of the platform and noted that there were incompatibilities and connectivity issues with learning devices (Hosseinpour et al., 2019 ). When communicating remotely, students pointed out that there were problems with the network and they were not able to connect and participate in learning process (Mohamadi Zenouzagh, 2018 ; Jung et al., 2019 ).

The Distribution of Technology in non-English Language Studies and Different Theories

This review also analyzed technologies that were used by those few studies that focused on non-English languages. This review found that, in general, scholars in these studies used such technologies as creative tools (Adobe Spark), collaboration tools (Google Docs), and social tool (Facebook) to present multimedia content to learners and support collaborative, creative and communicative learning activities (Valdebenito and Chen, 2019 ).

With regard to the distribution of technology in theory. Social constructivism theory was the most commonly cited theory in reviewed research and scholars used various technologies such as learning management systems (e.g., Moodle), creative tools (e.g., iMovie) or social tools (e.g., Facebook) to support constructivism-based learning activities. That is, interactive and collaborative learning activities were designed for students to learn new knowledge and then apply it to construct meaning in authentic contexts.

Based on the results of this study, several recommendations for educators and researchers were proposed. First, it is recommended that learning activities supported by technologies are designed based on appropriate theoretical foundation. Second, teachers are encouraged to conduct appropriate technology training for students beforehand so that they become familiar with technology tools. Third, teachers and researchers should test learning tools with students in advance in order to identify any possible technical problems, and provide timely support during learning process.

Learning Activities Used to Promote Language Skills and 21st Century Skills

This section describes what technologies are used in each type of learning activity and how they contribute to the development of learners' language skills and 21st century skills. In addition, it offers relevant suggestions to researchers and educators.

Adaptive Language Learning Activities on Learning Platforms

As shown in Table 1 , in the reviewed study, researchers used the following tools: Moodle, Google classroom, Quantum leap, and WebQuest, to develop adaptive language learning activities on learning platforms. These tools are used to integrate different types of instructional resources and diverse language learning activities to provide learners with adaptive learning materials that meet their learning needs. Students can ask questions and receive feedback from other students or teachers, and take control of their own learning progress.

Adaptive language learning activities on learning platforms.


Arnó-Macià and Rueda-Ramos ( )	Learning management system: Quantum LEAP	Online learning, complete listening, speaking, and reading tasks	Listening Speaking	Critical thinking
Yang et al. ( )	Learning management system: Moodle	Online learning, complete speaking and listening tasks	Listening Speaking	Critical thinking
Yang et al. ( )	Learning management system: Moodle	Online learning, complete reading, and writing tasks	Reading Writing	Critical thinking
Srebnaja and Stavicka ( )	Learning management system: WebQuests	Online learning, complete speaking and writing tasks	Speaking Grammar Writing	Creativity and innovation, collaboration, communication, digital literacy

For example, Arnó-Macià and Rueda-Ramos ( 2011 ) designed tasks for reading, listening, and speaking practice in Quantum leap platform. Researchers have designed listening tasks in Moodle platform; students were required to analyze, evaluate, and summarize content after listening (Yang et al., 2013 , 2014 ). Srebnaja and Stavicka ( 2018 ) designed WebQuests-based speaking and writing tasks.

All of these studies noted that learners' performance in speaking, listening, reading, writing, and grammar improved after completing the computer-assisted adaptive language learning tasks. In addition, students' critical thinking skills were developed.

Collaborative Task-Based Language Learning Activities

As shown in Table 2 , the following tools were used by researchers for the development of collaborative-based language learning activities: (1) collaboration tools: Google Docs, Google Drive, Wiki, Edmodo, and E-writing forum. These collaborative tools have the following functions: sharing, collaborative editing, cloud storage, synchronized display, and help students freely share information in various formats (e.g., text, images, videos, web links, audio recordings, music, etc.) on the platform so that they can exchange ideas and collaborate on editing content; (2) creative tools: Adobe Spark, to support students' expression of ideas; (3) social tools: Blogs or WordPress, to support students in reading and commenting on each other's work.

Collaboration-based language learning activities.


Amir et al. ( )	Social tools: Blog	Collaborate on writing tasks	Writing	Collaboration
García-Sánchez and Burbules ( )	Learning management system: Moodle Collaboration tools: Wiki	Students propose solutions to social problems	Speaking Vocabulary	Communication Collaboration Digital literacy Problem solving
Lai ( )	Collaboration tools: Padlet Creative tools: Home Styler, Thing Link	Collaborate on different tasks, such as creating vocabulary list, greeting cards	Vocabulary Grammar	Collaborative Communication
Mohamadi Zenouzagh ( )	Collaboration tools: E-writing forum	Collaborate on writing tasks	Writing	Collaboration
Valdebenito and Chen ( )	Creative tools: Adobe Spark, Google My Maps Collaboration tools: Google Doc, Word Press	Collaborate on culture tasks	Listening Speaking Writing vocabulary Grammar	Critical thinking Digital literacy Collaboration Communication
Huh and Lee ( )	Collaboration tools: Google Docs	Cooperate to complete role plays or songs to express the vocabulary learned	Speaking Writing	Creativity and innovation
Hosseinpour et al. ( )	Collaboration tools: Edmodo	Collaborate on writing tasks	Writing	Collaboration
Girgin and Cabaroglu ( )	Classroom interactive tools: Quizlet, Quizizz, Cram, Kahoot Creative tools: Story Bird, Voki, Go Animate, Animoto, Powtoon, Canva, Poster MyWall Collaboration tools: Padlet	Watch the video Collaborating on classroom tasks Creating digital stories Share and communicate	Listening Speaking Reading Writing Grammar vocabulary	Collaboration Critical thinking Creativity and innovation communication
Chen et al. ( )	Creative tools: Edu Venture Wearable devices: Google Cardboard	Solve problems and create videos collaboratively	Vocabulary	Problem solving

Collaboration-based language learning activities are those in which students work in groups to solve problems and complete tasks proposed by the teacher, such as asking students to provide an essay or present their ideas in other ways (e.g., a solution, a report, and a performance). For example, Amir et al. ( 2011 ) asked students to work in groups to publish six articles based on different topics over the course of 14 weeks, and one of the tasks required students to find and discuss software about computer-assisted writing.

Mohamadi Zenouzagh ( 2018 ) designed a collaborative writing activity based on the E-writing platform. Valdebenito and Chen ( 2019 ) designed a collaborative activity on the theme of “food and culture” in which students first had to use Google Maps to identify geographic areas related to the content, then use a Google Doc to record their ideas, and finally use video production tools such as Adobe Spark to express their ideas and share them on the WordPress platform. Huh and Lee ( 2020 ) designed a creative learning English collaborative activity in which students first used a mobile app to learn how to spell words, then the group took the words they learned and expressed them through the role play and song. Lai ( 2017 ) designed different collaborative tasks, for example, students needed to use the ThingLink tool to create vocabulary lists and greeting cards related to the topic, which were then shared on the Padlet platform and discussed. In addition, students were required to use HomeStyler to collaboratively design a dream home and use some vocabulary related to “location” to describe the design of their home.

Girgin and Cabaroglu ( 2021 ) designed an English learning project that integrates Web 2.0 technology and flipped classroom, and students used Padlet to watch videos in class. In grammar classes, students used Kahoot, Quizlet, Quizizz, Animoto, Powtoon, and Poster MyWall to answer grammar questions. In vocabulary and reading classes, students used tools such as Mind Meister, Voki, Canva, Cram, Go Animate and Story-bird to create mind maps, as well as create digital stories, which can be presented and shared. Chen et al. ( 2021 ) used virtual reality technology to design language learning activities. Learners were required to first watch a virtual reality scene and think about how to solve the problem based on a series of guiding questions provided by the teacher. Then students role-played in English to create a virtual reality video of the problem being solved.

The results of the abovementioned studies showed that collaborative-based language learning activities facilitated the development of learners' language skills. The researchers noted that collaborative problem-solving language learning activities provided learners with a large number of writing tasks, such as writing reports, essays, or creating storylines and designing works. The process of sharing with each other enabled to point out grammatical errors (Amir et al., 2011 ; Mohamadi Zenouzagh, 2018 ; Hosseinpour et al., 2019 ). When learners used multimedia resources to create vocabulary lists and greeting cards, their vocabulary and grammar skills were also improved (Lai, 2017 ).

At the same time, students' critical thinking was developed as they gave each other's critical and constructive comments (Valdebenito and Chen, 2019 ; Zou and Xie, 2019 ; Girgin and Cabaroglu, 2021 ). In addition, students completed tasks in small groups which promoted the development of communication and collaboration skills during discussions with each other (Amir et al., 2011 ; García-Sánchez and Burbules, 2016 ; Lai, 2017 ; Mohamadi Zenouzagh, 2018 ; Hosseinpour et al., 2019 ; Zou and Xie, 2019 ; Girgin and Cabaroglu, 2021 ). The process of students voicing digital content promoted the development of speaking skills (Huh and Lee, 2020 ). In the process of creating digital works, digital literacy was developed (García-Sánchez and Burbules, 2016 ; Valdebenito and Chen, 2019 ). Chen et al. ( 2021 ) pointed out that learners learn contextually in an immersive learning environment, and solving real problems through virtual reality technology improved learners' vocabulary as well as promoted their problem-solving skills.

Creative Work-Based Language Learning Activities

As shown in Table 3 , in reviewed studies, language learning activities based on creative works consisted of two main categories: creating digital stories or videos. The main models for this type of learning activity were as follows: students communicated in groups about how to create a digital story or video, then collected and processed relevant information, after that created a digital story, and finally shared content and communicated with each other about it.

Creative work-based language learning activities.


Thang et al. ( )	Creative tools: Photo Story3 Social tools: Blog	Create digital stories and share	Writing Speaking	Communication Creativity and innovation Collaboration ICT literacy
Sevilla-Pavón and Nicolaou ( )	Creative tools: iMovie, Inspiration Collaboration tools: Google Docs, Google Drive, Facebook, WhatsApp Presentation tools: PowerPoint, Prezi Social tools: Google+ Community, Google+ Forum	Create digital stories and share	Speaking Listening Reading Writing Vocabulary	Communication Collaboration Creativity and innovation Critical thinking Problem solving Digital literacy Social and cross-cultural interaction
Kulsiri ( )	Creative tools: Windows Movie Maker	Creative video	Speaking Reading Writing Vocabulary	Creativity and innovation Collaboration Problem-solving
Yalçin and Öztürk ( )	Learning management system: Google-classroom	Rewrite story endings, create digital stories and share	Writing	Communication Collaboration Creativity and innovation
Chiang ( )	Creative tools: Story Bird	Create digital stories and share	Writing	Digital literacy
Yang et al. ( )	Creative tools: Audacity Collaboration tools: Google Drive Presentation tools: Prezi	Create digital stories and share	Speaking	Creativity and innovation
Mirza ( )	Social tools: YouTube Presentation tools: PowerPoint	Create digital stories and share	Speaking	Communication
Huang ( )	Creative tools: Smartphone camera	Smartphone-based video creation	Speaking	Communication Digital literacy

The researchers chose different tools to support such learning process, e.g., (1) creating digital stories, i.e., Photo Story3, Windows Movie Maker, or iMovie; (2) creating video scripts in collaboration, i.e., Google Docs or Google Drive; (3) presenting digital stories, i.e., Prezi or PPT; (4) sharing digital stories and communicating, i.e., Google+ forums, Facebook, Instagram, WhatsApp, Google Classroom, and classroom management systems.

The researcher noted that digital storytelling promoted language skills, specifically, the process of writing story scripts promoted students' writing and vocabulary skills (Thang et al., 2014 ; Sevilla-Pavón and Nicolaou, 2017 ; Kulsiri, 2018 ; Yalçin and Öztürk, 2019 ; Chiang, 2020 ). It also promoted 21st century skills. Researchers mentioned three approaches for creating digital stories or videos such as free-writing, rewriting the ending of the story, and specifying the theme, and in this open-ended work creation process, students' sense of creativity, problem-solving skills, and digital literacy were developed (Thang et al., 2014 ; Sevilla-Pavón and Nicolaou, 2017 ; Kulsiri, 2018 ; Yalçin and Öztürk, 2019 ; Yang et al., 2022 ). Regarding the creation of digital stories on a specific theme, the researcher asked learners to design a new country, and students needed to understand a range of elements including different countries and cultures, such as national characteristics, language, national policies, climate and life. As a result, students' social and cross-cultural skills were improved. In addition, critical thinking was facilitated as students developed different ideas and perspectives as they evaluated each other's digital stories (Sevilla-Pavón and Nicolaou, 2017 ). Finally, students developed their communication and collaboration skills when working in groups (Thang et al., 2014 ; Sevilla-Pavón and Nicolaou, 2017 ; Kulsiri, 2018 ; Yalçin and Öztürk, 2019 ; Mirza, 2020 ; Huang, 2021 ).

Language Learning Activities Based on Multimedia Learning Materials

As shown in Table 4 , language learning activities based on multimedia materials involved such tools as (1) web-based learning management system, e.g., EDpuzzle; (2) social tool, e.g., YouTube; and (3) multimedia textbooks. All of them provided multimedia resources for students. There were also (4) collaboration tools, e.g., Padlet and Google docs, which supported learners to share ideas with each other.

Language learning activities based on learning multimedia materials.


Tseng ( )	Multimedia materials	Watch multimedia materials oral report and reflection on cultural differences	Listening	Social and cross-cultural interaction
Zou and Xie ( )	Learning management system: EDpuzzle Collaboration tools: Google Docs, Padlet	Watch video on writing skills, discuss in small groups and complete a report	Writing	Critical thinking Collaboration
Nikitova et al. ( )	Multimedia materials: Multimedia textbooks	Study multimedia materials and complete tasks	Speaking Writing Grammar Vocabulary	Collaboration Critical thinking Communication Problem solving
Aristizábal-Jiménez ( )	Multimedia materials: video	Watch YouTube videos and analyze, make videos and presentation	Vocabulary Grammar	Critical thinking

Scholars have designed a variety of language learning activities based on multimedia materials, but the topics and learning tasks of the multimedia materials involved in these studies differed. For example, Tseng ( 2017 ) asked learners to watch a video on the topic of cultural differences, and then students gave oral presentations and reflections to present their views on cultural differences. Zou and Xie ( 2019 ) asked students to watch a video on EDpuzzle, then to discuss in groups, negotiate and compare answers, to share their output to the Padlet platform, and finally submit their reports in Google docs. Nikitova et al. ( 2020 ) asked students to watch videos from multimedia textbooks with different English contexts and then simulated learners' role play activities. Aristizábal-Jiménez ( 2020 ) asked learners to watch YouTube videos, analyze the structure and content of video content, and then create posters to present and share their ideas.

The researcher noted that language learning activities based on multimedia materials promoted learners' language skills and 21st century skills. Specifically, learners' listening skills were promoted after watching the videos (Tseng, 2017 ). Culturally relevant content in videos and culture-based communication among peers promoted students' social and cross-cultural interaction skills (Tseng, 2017 ). Learners actively used dictionaries and discussed grammar while completing tasks to make the information easier to understand, which also promoted students' vocabulary and grammar skills (Aristizábal-Jiménez, 2020 ). In addition, working in groups to complete tasks promoted speaking, writing, grammar, and vocabulary skills. This was also beneficial to develop students' problem solving, collaboration, critical thinking, and communication skills (Aristizábal-Jiménez, 2020 ; Nikitova et al., 2020 ).

Language Learning Activities Based on Online Communication

As shown in Table 5 , the researchers designed online communication-based language learning activities. Most of them were cross-cultural communication activities to support cross-cultural communication between students from different cultural backgrounds. In terms of technology, the researchers mainly used social tools to support textual or video communication, e.g., Facebook, Skype, and WhatsApp. In addition, researchers have utilized learning management systems to support students to view learning resources uploaded by teachers.

Language learning activities based on online communication.


Calogerakou and Vlachos ( )	Multimedia materials: Film Social tools: Blog	Students from different cultural backgrounds watch films with culturally relevant backgrounds and communicate	Writing	Social and cross-cultural interaction Media literacy
Chen and Yang ( )	Social tools: ePals, iEARN, Skype	Students from different cultural backgrounds share culturally specific folklore stories, make videos, and perform puppet shows	Writing Vocabulary	Social and cross-cultural interaction Communication Collaboration
Lewis and Schneider ( )	Social tools: Skype	Students from different cultural backgrounds discuss cultural topics online	Speaking Grammar	Social and cross-cultural interaction Communication
Chen and Yang ( )	Learning management system: Moodle Social tools: Wiki	Students from different cultural backgrounds discuss movies with culturally diverse content online	Speaking Reading Writing Vocabulary	Social and cross-cultural interaction
Özdemir ( )	Social tools: Facebook, YouTube	Watch YouTube videos and discuss online based on cross-cultural questions prepared by the instructor	Writing Listening	Social and cross-cultural interaction
Sevy-Biloon and Chroman ( )	Social tools: Facebook, Skype, WhatsApp, Facetime	Students from different cultural backgrounds discuss cultural topics online	Speaking	Communication Social and cross-cultural interaction
Jung et al. ( )	Social tools: Live On	Students from different cultural backgrounds discuss cultural topics online	Grammar Vocabulary Speaking	Social and cross-cultural interaction
Hirotani and Fujii ( )	Social tools: Facebook	Students from different cultural backgrounds exchange proverbs online, write reflection journals and perform skits reflecting on cultural differences	Speaking Grammar	Communication Social and cross-cultural interaction
Jamalai and Krish ( )	Social tools: online forum (not specific)	Online topic discussion	Grammar Vocabulary Speaking	Critical thinking Digital literacy

The design of cross-cultural communication activities followed the same pattern—exposure to cross-cultural knowledge, reflection on cross-cultural differences, and cross-cultural exchange. For example, Calogerakou and Vlachos ( 2011 ) had students from two countries to watch movies and compare culture presented in movies with their own culture. Then students had to post comments on a blog and discuss their ideas. Chen and Yang ( 2016 ) asked students to share culturally specific folklore stories with their partners and to make videos of the stories to send to their partners. In addition, students were asked to perform a puppet show via videoconference. All of these were for students to learn about cultural similarities and differences. Chen and Yang ( 2014 ) designed a discussion activity based on cultural themes; for example, students discussed movies that involved culturally different content, and then students shared their opinions on Wiki. Lewis and Schneider ( 2015 ) asked learners to interact with native Spanish-speaking students and discuss cultural topics such as “local living conditions” and “how to celebrate holidays.” Learners were then asked to write a mini-biography or travel brochure for their study partner to demonstrate the cultural knowledge they gained during the exchange. Özdemir ( 2017 ) asked students to watch YouTube videos and discuss them based on cross-cultural questions prepared by the teacher. Sevy-Biloon and Chroman ( 2019 ) designed an intercultural exchange program in which students from Ecuador and the United States were randomly paired and then engaged in a cultural exchange based on the theme of the language course. Jung et al. ( 2019 ) asked students from different cultural backgrounds to discuss cultural topics, including “happiness factors, family, and food,” and finally, students reflected on the discussion, exchanged proverbs with each other, and then presented cultural differences. They reflected on their experiences in a reflective journal. Jamalai and Krish ( 2021 ) designed an online discussion activity, in which learners were required to engage in online discussions based on topics posted by teachers in a forum.

The results showed that students' speaking, vocabulary, writing, reading, and grammar skills improved when communicating through text and speech because students double-checked vocabulary spelling and grammar. Students identified errors they made when communicating using text and speech and corrected them to ensure that others understood their intended meaning (Calogerakou and Vlachos, 2011 ; Chen and Yang, 2014 , 2016 ; Lewis and Schneider, 2015 ; Özdemir, 2017 ; Hirotani and Fujii, 2019 ; Jung et al., 2019 ; Sevy-Biloon and Chroman, 2019 ; Jamalai and Krish, 2021 ). In addition, students' listening skills improved after watching YouTube videos (Özdemir, 2017 ).

At the same time, students' communication process using social tools developed the ability to use writing software, electronic dictionaries, and collect information on the Internet, and therefore media literacy was improved (Calogerakou and Vlachos, 2011 ). All studies point to the development of cultural interaction skills after students interacted and exchanged different cultural perspectives with partners (Calogerakou and Vlachos, 2011 ; Chen and Yang, 2014 , 2016 ; Lewis and Schneider, 2015 ; Özdemir, 2017 ; Hirotani and Fujii, 2019 ; Jung et al., 2019 ; Sevy-Biloon and Chroman, 2019 ). Communication (Chen and Yang, 2014 ; Lewis and Schneider, 2015 ; Hirotani and Fujii, 2019 ) and collaboration skills were also developed (Chen and Yang, 2014 ) in reviewed studies.

This review also analyzed learning activities that were used by those few studies that focused on non-English languages. This review found that most learning activities designed in these studies were online cross-cultural communicative activities. This shows that the primary goal of these learning projects was to develop students' foreign language and intercultural communication skills.

Based on the findings of the reviewed literature, the five types of language learning activities supported by technology had a positive impact on students' language skills as well as their 21st century skills development. Moreover, this review found that these learning activities followed similar pattern. The common pattern for language learning activities based on culture-related communication was exposure to cross-cultural knowledge, reflection on cross-cultural differences, and cross-cultural exchange. The common pattern of language learning activities for creative works was as follows: students communicated in groups about how to create a work (such as digital story or video), then collected and processed relevant information, created a work, and then shared content and communicated with each other about it. These patterns could provide suggestions for researchers and teachers to design similar instructional activities that target development of language skills and 21st century skills in the future.

Second, this review found that researchers designed similar instructional activities, but the research focus was different. For example, in the adaptive language learning activities on learning platforms, researchers focused on the development of students' speaking skills and lacked attention to reading skills. And in the collaborative task-based language learning activities, researchers have focused more on writing and vocabulary skills, collaboration, and communication skills, and lacked attention to listening skills. In creative writing-based language learning activities, researchers focused more on speaking and writing skills as well as creative and communication skills.

Research Duration, Participants' Academic Level, and Sample Size

The most common study samples were small ones with participants range from 11 to 30 ( n = 11) and medium samples with range between 61 and 90 ( n = 8) participants. Research durations were mostly between 3 and 6 months ( n = 10). Small sample size was acknowledged as a limitation in some studies (Hirotani and Fujii, 2019 ; Zou and Xie, 2019 ). The possible reason for this is that most of the studies were based on small classroom settings. In the reviewed studies, the most common academic level of participants was undergraduate level. There were 12 studies that did not specify research duration. Regarding this finding, there is a lack of attention in previous retrospective studies (Guan, 2014 ; Duman et al., 2015 ; Persson and Nouri, 2018 ).

Data Collection

Most of the studies collected both quantitative and qualitative data, which can help researchers to draw conclusions from different perspectives. Quantitative data included tests, scales, and rubrics; qualitative data included student's work, open-ended questions, student feedback, interviews, student chat transcripts, student reflections, teacher journals, and observations. One of the most common forms of quantitative data collection is a test ( n = 15), involving student language tests (tests of English speaking and listening) and tests of 21st century skills (critical thinking and creative thinking). The most common method of qualitative data collection was interview ( n = 13), where the researcher usually designed an interview outline and then asked learners questions to understand their learning experiences, attitudes, motivations, and challenges in the learning process. In addition, researchers have extensively used questionnaires ( n = 17), including both closed-ended and open-ended questions, to collect both quantitative and qualitative data. For example, the researchers used questionnaires to investigate learners' perceptions of technology-supported language learning, including effectiveness, usefulness, and students' perceptions of developing intercultural communicative competence and language skills through online discussions (Jung et al., 2019 ).

Based on the above findings, the recommendations of the present study for researchers and teachers are as follow. First, researchers could consider studies with longer time spans and collect data from bigger number of participants to investigate students' development over time and have generalizable conclusions. Second, researchers can collect multiple types of data, focus on students' learning processes and outcomes, and then interpret findings from different perspectives.

Research Design

There are a variety of research designs for reviewed studies on technology-supported language learning and 21st century skills. The most common are quasi-experimental studies. Such studies are characterized by using pre- and post-tests to measure changes in participants' language skills, 21st century skills and other learning outcomes and attitudes before and after participation in learning activities. In quasi-experimental studies, participants are not randomly assigned to an experimental or control group (Persson and Nouri, 2018 ; Huang, 2021 ). These findings are consistent with other reviews on technology-supported language learning (Persson and Nouri, 2018 ). The present study suggests that educators and researchers can use the three research methods mentioned above to validate their studies in future.

Positive Learning Experiences

In this section, the study discusses findings from reviewed studies and recommendations for educators and researchers. In reviewed studies, in addition to finding that technology-supported learning activities promoted learners' language skills and 21st century skills, researchers also found that these technologies led to positive learning experiences, which resulted in better learning outcomes. For example, learning through multimedia textbooks, collaborative blog-based writing activities, smartphone-based video filming activities and language learning projects based on intercultural exchange all increased students' motivation (Amir et al., 2011 ; García-Sánchez and Burbules, 2016 ; Sevy-Biloon and Chroman, 2019 ; Aristizábal-Jiménez, 2020 ; Huang, 2021 ). For example, Hosseinpour et al. ( 2019 ) noted that through collaborative writing activities, learners' motivation and self-confidence levels were increased. Mirza ( 2020 ) argued that through digital storytelling-based learning activities, students gained more confidence. Researchers have also looked at the different learning performance of students due to individual differences in abilities or their characteristics. Yang et al. ( 2014 ) found that in terms of writing, significant differences were found between “basic” and “low-intermediate” learners as a result of the difference in ability. Yalçin and Öztürk ( 2019 ) found that girls had a more negative attitude toward technology than boys.

Challenges Faced by Students

While many studies pointed to positive student attitudes toward technology-supported learning activities (Arnó-Macià and Rueda-Ramos, 2011 ; Girgin and Cabaroglu, 2021 ), several studies highlighted challenges that students faced when using technology for learning. Challenges from technology, with some learners finding it difficult to use in learning activities or being confused about the layout of mobile applications were mentioned. Students also noted problems with device incompatibility and poor network quality and speed when using technology. Self-competence challenges, with learners noting that learning tasks were difficult for them, for example, insufficient time to complete learning tasks, lack of research skills, or language skills needed to complete tasks, were reported. Difficulties in finding an interesting topic and choosing the right tools to create their work were also reported in reviewed studies. Challenges of collaborating with others, with some learners noting that they encounter uncoordinated teamwork, uneven distribution of work and unequal student contributions in collaborative tasks, were mentioned by scholars. Self-attitudes, as noted by learners who felt anxious about video chatting when they were communicating remotely, as well as fear of having their writing errors discovered by their partners when communicating in text, were reported in reviewed studies.

Based on the above findings, the present study recommends to educators and researchers, in addition to focusing on the impact of technology-supported learning activities on learners' language skills and 21st century skills, it is also important to focus on students' perceptions of technology, motivation, engagement, and confidence. This is because positive learning experiences can lead to better learning outcomes (Sevy-Biloon and Chroman, 2019 ; An et al., 2021 ). Regarding the technological challenges that students encounter in the learning process, it is recommended that they be addressed through advance trainings and through providing students with appropriate technological services during learning activities. Self-competence challenges can be addressed by designing collaborative tasks in which students with higher levels of competence can help students with lower levels of competence to complete the task. Regarding the challenges in collaborative activities, it is recommended that teachers and researchers design learning activities with clear rules for collaborative division of labor and rules regarding how learning performance of every learner will be evaluated. With regard to alleviating negative student attitudes, it is recommended that teachers design diverse teaching strategies and scaffolds to give students assistance during learning activities.

This study reviewed articles on technology-supported language learning and 21st century skills published from 2011 to 2022 (February) in terms of (a) research focus; (b) theoretical foundations; (c) technology; (d) learning activities; (e) methodology and (f) findings. The results indicate that research on technology-supported language learning and 21st century skills have shown an upward trend in the overall research in the covered time period, with most of the research focusing on English and the majority of participants in these studies majored in education.

Secondly, in terms of research focus, most of the researchers focused on learners' speaking skills (27.40%), followed by writing (26.03%) and vocabulary skills (17.81%). In terms of 21st century skills, most researchers focused on communication (20.83%), collaboration (20.83%), critical thinking (13.89%), and social and cross-cultural interaction skills (13.89%). In terms of theoretical foundations, social constructivist learning theory was most often adopted by researchers. In terms of technology, tools that support learners' creativity and socialization are often utilized by researchers, e.g., Facebook or Google Docs. In terms of learning activities, researchers have designed the following five types of learning activities to support learners' language learning and 21st century skills: (1) collaborative task-based language learning activities; (2) language learning activities based on online communication; (3) creative work-based language learning activities (4) adaptive language learning activities based on learning platforms; and (5) language learning activities based on multimedia learning materials. The results of reviewed studies indicate that these learning activities supported by technology are effective in promoting the development of learners' different language skills and 21st century skills. Finally, in terms of methodology, most of the studies had a sample of 11–30, the most common study period was 3–6 months, the data collection method often used by researchers was questionnaires, the most common method to collect quantitative data was tests, and the most common method to collect qualitative data was interviews.

In contrast to traditional paper and pencil-based learning, technologies used by researchers in reviewed studies allowed learners to improve language learning outcomes and 21st century skills through individual and collaborative learning activities. Some reported advantages are learning with technologies without the constraints of time and space, technologies enable personalized learning, technologies create authentic learning environments that provides adaptive learning content, helps create multimedia content actively, allows social interaction such as sharing, giving or receiving feedback, and reflecting on learning more efficiently.

Based on the above findings, recommendations for researchers and educators in this study include: (1) In terms of language skills, in addition to focusing on output skills, input skills (reading, listening) also deserve attention from researchers. In terms of 21st century skills, learners' problem-solving skills and career and life skills also need more attention from researchers in the future; (2) Advanced technology training for learners to familiarize them with technology and its effective usage as well as teachers need to check in advance for possible technology problems, such as network problems. These suggestions can help teachers address the technological barriers that learners encounter in the learning process; (3) The use of various theoretical approaches, such as instructional design-related theories and language learning-related theories, is important for the rational design of instructional activities that promote learners' language and 21st century skills; (4) Researchers and educators can follow the general model of conducting the five types of instructional activities summarized above to design instructional activities. In addition, it is recommended that researchers and educators use variety of technologies and design different instructional activities to promote learners' language and 21st century skills. It is also important to be aware of the challenges that students may encounter in terms of technology, learning activity tasks, peer collaboration and self-attitudes when implementing learning activities; (5) Teachers and educators could involve more participants and consider longer time spans in future studies to focus on more learners' development and to collect diverse quantitative and qualitative data to explain students' learning processes and outcomes.

There are few limitations to this study. Articles reviewed in this study were sourced from PRIMO and Web of Science databases, and some conference papers, books and dissertations were excluded. For this reason, this study reviewed smaller number of articles. Future studies may consider this limitation and address it by including more relevant sources.

Data Availability Statement

Author contributions.

RS and XW contributed to the conception, designed the work, collected the data, analyzed, and interpreted data. XW drafted the work and RS substantively revised it. RS was responsible for correspondence. All authors approved the submitted version and agreed both to be personally accountable for the author's own contributions and to the accuracy the work.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher's Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

1 Articles reviewed in this study.

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpsyg.2022.897689/full#supplementary-material

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FIP indicates International Pharmaceutical Federation.

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Ashraf AR , Mackey TK , Schmidt J, et al. Safety and Risk Assessment of No-Prescription Online Semaglutide Purchases. JAMA Netw Open. 2024;7(8):e2428280. doi:10.1001/jamanetworkopen.2024.28280

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Safety and Risk Assessment of No-Prescription Online Semaglutide Purchases

1 Department of Pharmaceutics, Faculty of Pharmacy, University of Pécs, Pécs, Hungary
2 Global Health Program, Department of Anthropology, University of California San Diego, La Jolla
3 Global Health Policy and Data Institute, San Diego, California
4 S-3 Research, San Diego, California
5 Institute of Biochemistry and Medical Chemistry, Medical School, University of Pécs, Pécs, Hungary
6 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Pécs, Pécs, Hungary

The popularity of branded semaglutide is surging, with widespread media coverage, viral social media exposure, and celebrity endorsements. 1 Although Wegovy (Novo Nordisk) is approved for long-term weight management, Ozempic (Novo Nordisk) (only approved for type 2 diabetes) is often used off-label for this purpose. Global regulatory agencies, including the US Food and Drug Administration (FDA), European Medicines Agency, and World Health Organization (WHO), have warned about fake versions driven by patient demand, high cost, and shortages. Illegal online pharmacies, which operate without valid licenses and sell medicines like semaglutide without prescription, represent a consumer risk for ineffective and dangerous products.

In this qualitative study, we conducted risk assessment of semaglutide online sourcing ( Figure and eAppendix in Supplement 1 ). We followed the SRQR reporting guideline.

First, we conducted structured searches on Google and Bing to catalog websites advertising semaglutide without a prescription in July 2023. Websites meeting inclusion criteria were selected for a product test buy protocol. 2 Two 0.25-mg per dose prefilled pens or equivalent semaglutide injection vials were ordered from each website. Upon product receipt, authors (A.R.A., and A.F.) used the International Pharmaceutical Federation’s (FIP) checklist for visual inspection to assess potential counterfeiting or falsification risks, compared with genuine Ozempic brand 1-mg semaglutide solution for injection in a prefilled pen. 3 Products were then tested for quality, including sterility and microbiological contamination, according to European Pharmacopoeia and US Pharmacopeia guidelines. Quantification of active ingredients was performed using liquid chromatography–mass spectrometry (LC-MS). Test purchases and analytical testing were performed August from 2023 to March 2024.

Search engine monitoring generated 1080 hyperlinks, with 317 (29.35%) for online pharmacies. Nearly one-half (134 sites [42.27%]) belonged to illegal pharmacy operations; 763 links were websites not offering products for sale, including 615 news and informational websites and 148 telemedicine websites requiring consultation to obtain prescription before purchase.

Six online vendors classified as not recommended or rogue by LegitScript and/or National Association of Boards of Pharmacy and offering parenteral semaglutide products were included in test buys. Three websites offered prefilled 0.25-mg per dose semaglutide injection pens, and 3 sold vials of lyophilized semaglutide to be reconstituted to solution for injection (1-3 mg). All vendors referred to weight loss and obesity on their product page. Prices for the smallest dose and quantity ranged from US $113 to $360 (mean [SD], US $218.5 [$93.6]) ( Table ).

Test purchases were confirmed via email and WhatsApp. Of 6 products purchased, only 3 were received. Three vendors selling Ozempic injections engaged in nondelivery scams requesting extra payments (range, US $650-$1200) to purportedly clear customs, confirmed as fraudulent by customs agencies. Although genuine Ozempic scored the full 22 points on the FIP checklist, test purchased products scored 8 or 9 with clear discrepancies in regulatory registration information, accurate labeling, and evidence products were likely unregistered or unlicensed.

Upon quality testing, one sample had elevated presence of endotoxin (8.95 EU/mg) indicating possible contamination, although no viable microorganisms were detected. LC-MS revealed the presence of semaglutide in all samples, but with considerably lower purity levels (7%-14% vs advertised 99%). The measured semaglutide content substantially exceeded the labeled amount in each sample by 29% to 39%, meaning that users could receive up to 39% more semaglutide per injection. These risk factors indicate likely falsification that does not meet legitimate product quality standards.

This qualitative study found that semaglutide products are actively being sold without prescription by illegal online pharmacies, with vendors shipping unregistered and falsified products. Two websites evaluated were sent FDA warning letters for unlawful sale of unapproved and misbranded semaglutide. 4 , 5 US poison centers have reported a 1500% increase in calls related to semaglutide, highlighting the need for enhanced pharmacovigilance including for online sourcing harms. 6 Study limitations include limited sample of products tested due to nondelivery scams. Furthermore, although tested products represent some accessible semaglutide products sold online, higher priced offerings were excluded, limiting generalizability of the findings.

Accepted for Publication: June 21, 2024.

Published: August 2, 2024. doi:10.1001/jamanetworkopen.2024.28280

Corresponding Author: Tim K. Mackey, MAS, PhD, Global Health Program, Department of Anthropology, University of California San Diego, 9500 Gilman Dr, MC 0505, La Jolla, CA 92093 ( [email protected] ).

Author Contributions: Dr Ashraf had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Ashraf, Mackey, Vida, Li, Fittler.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Ashraf, Mackey, Kulcsár, Vida, Fittler.

Critical review of the manuscript for important intellectual content: Ashraf, Mackey, Schmidt, Kulcsár, Li, Fittler.

Statistical analysis: Ashraf, Kulcsár, Li.

Obtained funding: Mackey, Fittler.

Administrative, technical, or material support: Ashraf, Mackey, Vida, Li.

Supervision: Mackey, Fittler.

Conflict of Interest Disclosures: Mr Schmidt reported receiving grant TKP2021-EGA-17 from the Hungarian National Research, Development and Innovation Office outside the submitted work. No other disclosures were reported.

Funding/Support: The research was supported by the Hungarian Scientific Research Fund (grant NKFI-ID 143684).

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Data Sharing Statement: See Supplement 2 .

Additional Contributions: The research was performed in collaboration with Mass Spectrometry Core Facility at the Szentágothai Research Centre of the University of Pécs.

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Advances in research on bacterial oxidation of mn(ii): a visualized bibliometric analysis based on citespace.

1. Introduction

2. materials and methods, 2.1. data source and retrieval strategy, 2.2. data analysis and visualization, 3.1. trend analysis of annual publications, 3.2. analysis of countries and institutions, 3.3. analysis of disciplinary classifications, 3.4. analysis of authors of co-occurrence and co-citation, 3.5. analysis of journal citations, 3.6. analysis of co-cited references, 3.7. analysis of temporal and burst of keywords, 3.8. analysis of keyword clusters, 4. discussion, 4.1. research hotspots and trends, 4.1.1. species and ecological distribution, 4.1.2. factors influencing bacterial mn(ii) oxidation, 4.1.3. mechanisms of mn(ii) oxidation in bacteria, 4.1.4. environmental applications, 4.2. outlook, 5. conclusions, author contributions, data availability statement, conflicts of interest.

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Click here to enlarge figure

Rank	Country	Count	Rank	Country	Centrality
1	China	197	1	USA	0.38
2	USA	128	2	China	0.34
3	Japan	33	3	Germany	0.15
4	Germany	20	4	Netherlands	0.14
5	India	18	5	England	0.09
6	Canada	11	6	Japan	0.04
7	England	10	7	South Korea	0.04
8	France	9	8	Pakistan	0.04
9	Australia	8	9	Mexico	0.04
10	South Korea	9	10	France	0.03

Rank	Count	Centrality	Institution	Country
1	41	0.19	Chinese Academy of Science	China
2	28	0.06	Harbin Institute of Technology	China
3	27	0.23	Oregon Health and Science University	USA
4	20	0.07	Huazhong Agricultural University	China
5	14	0.00	University of Chinese Academy of Sciences	China
6	12	0.00	Xi’an University of Architecture and Technology	China
7	9	0.05	Hiroshima University	Japan
8	8	0.04	Woods Hole Oceanographic Institution	USA
9	8	0.03	Smithsonian Institution	USA
10	8	0.00	Beijing University of Technology	China

Rank	Category	Count	Rank	Category	Centrality
1	Environmental Sciences & Ecology	151	1	Environmental Sciences & Ecology	0.41
2	Environmental Sciences	122	2	Chemistry	0.41
3	Engineering	87	3	Biotechnology & Applied Microbiology	0.39
4	Microbiology	73	4	Biochemistry & Molecular Biology	0.34
5	Engineering, Environmental	72	5	Environmental Sciences	0.32
6	Biotechnology & Applied Microbiology	52	6	Engineering	0.18
7	Water Resources	39	7	Chemistry	0.18
8	Geology	32	8	Microbiology	0.15
9	Geosciences	28	9	Agriculture	0.14
10	Biochemistry & Molecular Biology	25	10	Toxicology	0.09

Rank	Top Ten Productive Author	Count	Rank	Top Ten Co-Cited Author	Citation
1	Tebo BM	22	1	Tebo BM	212
2	Bai YH	13	2	Francis CA	104
3	Qu JH	12	3	Learman DR	94
4	Zhang J	10	4	Villalobos M	89
5	Pan XL	9	5	Geszvain K	87
6	Hansel CM	8	6	Dick GJ	80
7	Liu F	8	7	Webb SM	79
8	He ZF	7	8	Miyata N	74
9	Santelli CM	7	9	Anderson CR	71
10	Wei Z	7	10	Brouwers GJ	69

Rank	Citation	Cited Journal	IF	JCR	Country
1	301	Applied and Environmental Microbiology	4.32	Q2	USA
2	232	Environmental Science & Technology	11.09	Q1	USA
3	223	Water Research	12.75	Q1	England
4	214	Geochimica et Cosmochimica Acta	4.97	Q1	USA
5	205	Geomicrobiology Journal	2.30	Q3	USA
6	188	Journal of Bacteriology	3.06	Q3	USA
7	180	Proceedings of the National Academy of Science of the United States of America	10.71	Q1	USA
8	168	Annual Review of Earth and Planetary Sciences	14.29	Q1	USA
9	158	Chemosphere	8.80	Q1	England
10	153	PLoS One	3.64	Q2	USA

Title	Authors	Year	Citation Frequency
Synergistic effects of biogenic manganese oxide and Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1 on the degradation of 17 α-ethinylestradiol	Tran TN et al. [ ]	2018	30
A novel manganese oxidizing bacterium-Aeromonas hydrophila strain DS02: Mn(II) oxidization and biogenic Mn oxides generation	Zhang Y et al. [ ]	2019	29
Elimination of Manganese(II,III) Oxidation in Pseudomonas Putida GB-1 by a Double Knockout of Two Putative Multicopper Oxidase Genes	Geszvain K et al. [ ]	2013	27
Mn(II, III) oxidation and MnO mineralization by an expressed bacterial multicopper oxidase	Butterfield CN et al. [ ]	2013	23
Diverse manganese(II)-oxidizing bacteria are prevalent in drinking water systems	Marcus DN et al. [ ]	2017	22
Effective start-up biofiltration method for Fe, Mn, and ammonia removal and bacterial community analysis	Cai YN et al. [ ]	2015	22
Extracellular haem peroxidases mediate Mn(II) oxidation in a marine Roseobacter bacterium via superoxide production	Andeer PF et al. [ ]	2015	21
CotA, a multicopper oxidase from Bacillus pumilus WH4, exhibits manganese-oxidase activity	Su JM et al. [ ]	2013	21
Formation of manganese oxides by bacterially generated superoxide	Learman DR et al. [ ]	2011	20
Identification of a third Mn(II) oxidase enzyme in Pseudomonas putida GB-1	Geszvain K et al. [ ]	2016	20

Rank	Keyword	Frequency	Centrality
1	Mn(II) oxidation	104	0.08
2	oxidation	92	0.16
3	iron	81	0.19
4	identification	65	0.10
5	removal	62	0.09
6	multicopper oxidase	61	0.04
7	water	42	0.06
8	oxides	42	0.07
9	spores	38	0.07
10	mechanisms	38	0.06
11	manganese oxidation	38	0.05
12	biogenic manganese oxides	34	0.09
13	microbial community	32	0.11
14	bacteria	32	0.08
15	adsorption	32	0.13

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Mo, W.; Wang, H.; Wang, J.; Wang, Y.; Liu, Y.; Luo, Y.; He, M.; Cheng, S.; Mei, H.; He, J.; et al. Advances in Research on Bacterial Oxidation of Mn(II): A Visualized Bibliometric Analysis Based on CiteSpace. Microorganisms 2024 , 12 , 1611. https://doi.org/10.3390/microorganisms12081611

Mo W, Wang H, Wang J, Wang Y, Liu Y, Luo Y, He M, Cheng S, Mei H, He J, et al. Advances in Research on Bacterial Oxidation of Mn(II): A Visualized Bibliometric Analysis Based on CiteSpace. Microorganisms . 2024; 12(8):1611. https://doi.org/10.3390/microorganisms12081611

Mo, Wentao, Hang Wang, Jianghan Wang, Yue Wang, Yunfei Liu, Yi Luo, Minghui He, Shuang Cheng, Huiting Mei, Jin He, and et al. 2024. "Advances in Research on Bacterial Oxidation of Mn(II): A Visualized Bibliometric Analysis Based on CiteSpace" Microorganisms 12, no. 8: 1611. https://doi.org/10.3390/microorganisms12081611

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Language Acquisition Theory

Behaviorist Theory of Language Acquisition

Chomsky Theory of Language Development

Universal Grammar

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What is language acquisition?

What is Skinner’s theory of language development?

What is Chomsky’s theory of language acquisition?

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Early language acquisition: cracking the speech code

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The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis

Introduction

Delineating the scope of the critical period hypothesis

Formulating testable hypotheses

Inferring non-linearities in critical period research: An overview

Group mean or proportion comparisons.

Comparison of correlation coefficients.

Regression approaches.

Summary of DeKeyser et al. (2010)

Data extraction

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On partialling out ‘age at testing’

On estimating the role of aptitude

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Supporting Information

Dataset S2.

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A Review of Research on Technology-Supported Language Learning and 21st Century Skills

Introduction

Research Method

Research Focus

Theoretical Foundation

Learning Activity

Methodology

Language Skills

21st Century Skills

Theories Related to Instructional Design

Theories Related to Language Learning

Theories Related to Measuring Learning Outcomes

Eight Technologies With Different Functions

Most Commonly Used Technologies

Experienced Challenges of Using Technology

The Distribution of Technology in non-English Language Studies and Different Theories

Learning Activities Used to Promote Language Skills and 21st Century Skills

Adaptive Language Learning Activities on Learning Platforms

Collaborative Task-Based Language Learning Activities

Creative Work-Based Language Learning Activities

Language Learning Activities Based on Multimedia Learning Materials

Language Learning Activities Based on Online Communication

Research Duration, Participants' Academic Level, and Sample Size

Data Collection

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Positive Learning Experiences