SECOND LANGUAGE LEARNERS’ AGE: A CASE STUDY OF SELECTED NON-NATIVE SPEAKERS OF ENGLISH
CITATION: Oluwole, J. (2024), ‘Second Language Learners’ Age: A Case Study of Selected Non-native speakers of English’, Journal of Social Science Student Research, Volume 2, DOI:
SECOND LANGUAGE LEARNERS’ AGE: A CASE STUDY OF SELECTED NON-NATIVE SPEAKERS OF ENGLISH
ABSTRACT
Debates on the ideal age to learn the English language as a second or foreign language continue to permeate the field of applied linguistics. While some research concludes that the earlier a learner is exposed to the target language, the better, others are of the opinion that later access to a second or foreign language might be more advantageous. Employing selected non-native speakers of English as a case study, this research attempts to examine both sides of the argument.
A qualitative research design was employed, using in-depth interview as the data gathering tool, with 4 participants. The findings of the study show that both earlier and later access to a second language tend to have unique benefits and shortcomings. While second language learning should be encouraged to start at earlier ages, adult learning should also be supported and promoted, as the maturity capacity can be advantageous in the learning process if appropriately harnessed.
Keywords
Second/foreign language, applied linguistics, target language, non-native speakers, critical period hypothesis, reflexive thematic analysis, Lingua Franca.
Introduction
Most human beings naturally acquire a language, usually the language of immediate environment (Berko and Bernstein 2009). This is generally known as the first language or L1 (Ortega, 2009) while any additional language learnt or acquired is referred to as the second language (L2), which can be another local language or a foreign language (Singleton and Ryan, 2004). Learning a second language with its distinct social, cultural, and linguistic features from the mother tongue can be challenging due to certain concerns surrounding this process (Creswell, 2009).
The factors that influence L2 learning, such as age, gender, socio-economic status, ethnicity, religion, geographical location, internal/external motivation, continue to be the subject of differing perspectives among applied linguistics researchers (Ortega, 2009; Meisel, 2016; Singleton and Leśniewska, 2021; Liquin and Gopnik, 2022). While some suggest that young learners of a second language who have early access to the target language from childhood are likely to learn quickly (Flege and Liu, 2000; Meisel, 2016; Liquin and Gopnik, 2022), others hold that adults can be more advantaged because their maturity and metalinguistic awareness could play a significant role in learning the target language (Singleton and Pfenninger, 2018; Hsiao and Oxford, 2022). This remains a debate in the field of applied linguistics.
Aim and objective
The aim and objective of this study was to investigate the effects of second language learner age factor in the learning process. This provides valuable insights for educators working with second language learners at different ages.
Literature Review
The ideal age to learn a second or additional language remains a debate in second language acquisition research. A handful of studies have been conducted on second language acquisition concerns specifically on how learners’ age factor positively or adversely contributes to the learning process, suggesting the ideal age to learn a second or additional language (Chu, 2006; Meisel, 2008; Gawi, 2012; Singleton and Pfenninger, 2018; Liquin and Gopnik, 2022). The related research will be reviewed in this section drawing inferences from diverse perspectives.
Second language acquisition theories such as Chomsky’s Native theory, Krashens’ input hypothesis, Skinner’s behaviourists theory, the noticing hypothesis, sociocultural theory, the critical period hypothesis (CPH) and emergentist account offer diverse perspectives on how language is acquired, providing insights that contribute to the knowledge of second language acquisition/learning. This study will examine some of the arguments of these theories and the findings of this study will both validate and rescind some of these theories.
The emergentist account argues for a dynamic perspective on language learning with an interplay between cognitive capacities, contextual input, and usage behaviour. One of the key theories of the emergentist account is the usage-based theory of language acquisition proposed by Tomasello (2003). It argues that language organization and development emanate from language use, and young children tend to build their language relying on its use in meaningful communication rather than intrinsic linguistic knowledge. This argument seems to contradict the CPH’s assumption about language acquisition.
The CPH is associated with the innate perspective towards language learning (Flege and Liu, 2000). Advocates hypothesize that when learners are exposed to a language at an early childhood stage, they tend to learn easily and efficiently, even up to a native-like proficiency level (Scovel, 2000). In contrast, adults may never be able to gain proficiency even with the aid of carefully designed resources and competent teachers in the target language, due to their limiting age factor (Lightbown and Spada, 2013). However, research has revealed the inconsistency of this perspective. Adult learners tend to achieve high levels of proficiency, especially in grammar and vocabulary, due to their advanced cognitive abilities; they also demonstrate faster learning rates than young learners and often experience significant learning gains when placed in similar immersion and naturalistic contexts (Marinova-Todd et al., 2000; Clark and Clark, 2019).
Gawi (2012) investigated early access to second language learning in the Saudi Arabia context. The study identified significant differences between students who started learning English early (age 6 and below) and those who learnt at later ages (12 and above), employing both English teachers who were non-native speakers of English and elementary school students who were L1 Arabic speakers of different age groups in both public and private school settings as a case study. It examined how learner age affects both the teaching and learning process.
This study advocated for English language learning at an early age, as it found that young learners tend to learn more effortlessly than their older pairs. Young learners learning outcomes seem better in all four English skills of listening, speaking, reading, and writing, as against their older counterparts, who seem to have weaker acquisition of these skills. The findings of this study, however, seem to have ignored the advantages older learners of a second language might have over the younger ones, such as their developed metalinguistic capacities and maturity, as evidenced by Singleton and Pfenninger (2018), and Chu (2006). For a holistic view of learner age effect on the learning process, this current study considered areas where young learners seem to have an edge, not leaving out areas where adult learning can be advantageous.
Singleton and Leśniewska (2021) and Liquin and Gopnik (2022) seem to have contradicting views regarding the age factor in second language learning. While the former advocates against the ‘critical period’, the latter supports that the ideal age to learn is at childhood. Liquin and Gopnik suggest that young learners tend to be more active and explorative than adults, and in the process, have more awareness about their environment. It gives credence to the hypothesis that children may be more adventurous than adults and that this greater exploration influences learning abilities. In contrast, Singleton and Leśniewska (2021) attempted to draw a line of conclusion from speculation surrounding the CPH. It advocates against ‘the younger the better’ trend, evidencing that over time, adult learners can perform as well in L2 learning as young learners. This seems to be critical of the CPH, as it places young and adult learners’ learning abilities side by side. Furthermore, they argued that the actual age a second language learner is exposed to the target language should not be a benchmark because non-biological factors such as motivation, learning environment, exposure, and educational background also play vital roles in the learning process.
Other CPH advocates project that there is a specified age range at which L2 learners can optimally internalize a target language. This is variously age 3-4 (Meisel, 2016), age 1-6 (Doughty and Long, 2003), pre-age 9 (Dollmann et al., 2020), or pre-age 17 (Hartshorne et al., 2018).
Kuhl (2011) argues that advantages with L2 acquisition end with puberty. This then raises another question of the actual age of puberty because the age bracket of puberty has never been constant (sometimes between 8 and 15). Puberty can sometimes be gender determinant, as Roberts (2013) asserts that puberty tends to occur later in males than females. More so, it has been discovered that girls may sometimes start experiencing puberty on or before the age of six (Biro et al., 2020). Whereas there have been extreme cases of children who did not experience puberty until their late teens of 18–19 (Abdel Aal, 2016). As a result, it is challenging to establish a precise boundary and, therefore, challenging to make claims about the onset and offset of the ‘critical period’.
Methodology
The epistemological approach in this study is interpretive. This stems from the belief that all knowledge is relative to the knower and can only be understood from the point of view of individuals who are directly involved. In that, truth is socially constructed through multiple interpretations by the subjects of the knowledge (Creswell, 2009; Sarantakos, 2013; Chen et al., 2018; Leavy, 2017). This study enables the participants to provide a holistic assessment of the role of age in second language acquisition from a subjective point of view, drawing from their personal experiences. Hence, the ontological paradigm of this study is that of relativism—no single reality exists, as reality is relative to how individuals experience it (Sarantakos, 2013).
A qualitative study design was also chosen for data collection, analysis, and interpretation, as it tends to suit the interpretive viewpoint (Creswell, 2009). The data gathering tool employed in this study is in-depth interview. This was necessary to draw descriptive, practical, and first-hand data (Walker, 2010).
Participants for this study are four non-native speakers of English; students at a University in Scotland. Pilot work preceded this research and participants for the pilot study were 4 non-native speakers of English in a language school. The purpose of the pilot study was to test the research tools and confine the scope of this study. The pilot study was also necessary to test the feasibility of the purposive sampling method which was employed in the final data collection (Dörnyei, 2007; Abello-Contesse, 2008; Gass and Selinker, 2008; Birdsong, 2017).
Ethics, data sampling, collection, and analysis
Having obtained ethical approval from the University ethics committee, potential participants were invited to participate in the study. Positive responses were received from students from Sri Lanka, Nigeria, China, and India. As a result, a purposeful sampling approach was adopted, and one participant was selected from each country (Bhardwaj, 2019). Participants for this study were intended to be from diverse linguistic backgrounds and of different first language (L1) to add international relevancy to the study.
Data for this study was collected through interview via Microsoft Teams, one each with participants (Miyahara, 2020). The interview transcripts were edited before sending to participants for respondent validation to ensure their responses were well captured and to point out any error in the edited transcript (Harvey, 2019; Birt et al., 2016; Candela, 2019). Afterwards, the transcripts were repeatedly read for familiarization . This helped to find any significant nuances in context and enhanced the coding, overall theme formation, and critical perception of the data.
Microsoft Word features enabled the generation of initial codes. The codes were generated using chromatic features (colour coding). Green for Nigeria, orange for Sri Lanka, red for China and blue for India. This was necessary to enhance data visualization and identification (Bianco et al., 2019). These codes were then refined to generate more specific themes and sub-themes in alignment with the research concerns. An interpretation of the results with a recourse to previously reviewed literature supported the analysis procedure. In analysing the data, reflexive thematic analysis (RTA) was employed (Clarke et al., 2019; Roberts et al., 2019; Braun and Clarke, 2021). This is because RTA allows a depiction of the researcher’s interpretation of the data carried out at the confluence of the dataset, analytical framework, and the researcher’s analytical capabilities and resources (Braun and Clarke, 2021).
Ethical consideration
Participants were informed of their rights, encouraged to choose a time and place for interview according to preference, and all data was anonymised (Cohen et al., 2011; Braun and Clarke, 2020). All these points were captured in the participant information sheet and consent form and restated at the beginning of the interviews. For the discussion of results the participants will be anonymised and referred to only by the initials S, N, I and J.
Results and discussion
Experiences of age impact on L2 acquisition:
It was found through the interview sessions that participants (S and N) learnt English at earlier years -ages 2 and 3, (I) learnt as a teenager (age 15), while the fourth participant (J) learnt as an adult (age 30).
Participants Sand N from Nigeria and Sri Lanka respectively, started learning English at an earlier age, 3 and 2 respectively. One of the reasons for their early exposure to English was the high status of English in their home countries, as the English language has gained prominence in almost every sector, including education, trade and commerce, sports, and entertainment (Iwuchukwu and Iwuchukwu, 2018; Gunesekera, 2010). Iwuchukwu and Iwuchukwu (2018) noted that English has been a mandatory subject at all levels of education both in public and private schools in Nigeria. It serves as a lingua franca or unifying language. Since Nigeria is a multi-cultural linguistic community, there was a need for a unifying means of communication to bridge the multi-linguistic gap. The advent of colonialism in the 19th century by the British introduced formal education with English as a medium of instruction in Nigeria (Sherif, 2019). The English language was used to enhance comprehension between citizens and the colonial leaders and to bridge the intercultural differences in the country. This might have enhanced its wide use in every sector today.
Similarly, the medium of instruction in Sri Lankan government-owned schools has been the local languages up until 2001 (Wijaytunga, 2018). English was merely taught as one of the school subjects until then. The government afterwards adopted English as the primary medium of instruction to optimally prepare the next generation for globalisation. Irrespective, participant Sbelieved that the quality of English input was still substandard and minimal, especially in government-owned schools compared to private schools, adding that the implementation of English as a medium of instruction has been uneven, as it has not been properly enacted, especially in the rural areas. These could have been caused by inadequate English teaching materials, lack of competent English teachers, lack of proper planning, and government apathy, among other reasons.
Participant S further noted that, prior to the beginning of the 21st century, many people seem to be driven to learn English due to its associated status in society. This factor influenced parents to enrol their children in private schools at earlier ages, where English serves as the medium of instruction, possibly suggesting parental belief that the ideal stage to acquire a second language is during childhood. This belief resonates with Singleton and Ryan’s (2004) argument of ‘the younger the better’ supporting that children tend to learn the target language effortlessly, especially when optimum input is available.
Dollmann et al. (2020) posited that young learners of a second language, who have early access to the target language from childhood are likely to pick it up quickly. This idea correlated with the experiences of participants Sand N, as they affirmed that their early exposure to English language had a positive impact on L2 learning. This further corroborates Chu’s (2006) view that children are believed to learn a second language without stress, especially the production skills (writing and speaking) compared to adult learners who might struggle with the learning process. Furthermore, this finding appears to support the critical period hypothesis.
However, it was found that even though participant Jlearnt English as an adult, it still had positive implications. They stated that there was no opportunity to learn English at all throughout their childhood period. The determination to study abroad brought about the need to learn the English language. This late exposure to English was not a disadvantage, and itwas clear that they did not see themself disadvantaged and identified that the time was right to learn English. This could be due to personal motivation to learn English and a desire to undertake further study abroad.
The above perspective resonates with Singleton and Leśniewska’s (2021) view that challenges the superiority of early-age L2 learning. Evidencing that in the long run, like young learners, adult learners may have a propensity for success in second language learning. Participant Jeventually learnt English within one year and enrolled in a Masters-level programme delivered and assessed in English. This is a significant success contradicting the extreme position of CPH advocates.
It was a different experience, however, for participant I, who also learnt English at a later age. Unlike participant J, participant Iwas exposed to English in primary school, but did not learn optimally until age 15. This could have been because English was mostly taught as one of the school subjects at early education levels in their country. The medium of instruction was mostly the local languages, with exemptions in the case of some private schools (Landow, 2013). They also expressed their regret for not learning English earlier. In essence, the inability to learn English optimally was due to late exposure to sufficient English input, which corroborates the critical hypothesis argument.
Optimal age for L2 acquisition:
Given that it is generally assumed that learning outcomes of a second language depend largely on the age of the learner (Pfenninger and Singleton, 2019), the question regarding the most effective age to start learning a language remains a debate in second language acquisition studies. Participants in the current study had a variety of views regarding the ideal age to learn a second language, drawing conclusions based on their personal experiences.
Although some participant experiences challenged the idea of CPH in effective L2 acquisition they also affirmed that it may be more advantageous to learn English at an earlier age. Irrespective of the differing experiences of when a second language was learnt, they all eventually concluded that it is more effective to begin the learning process from childhood.
Liquin and Gopnik (2022) validated the widely held claim of ‘the younger the better’ in a study where young children outperformed their adult counterparts. Some CPH critics have argued against their findings, objecting that while greater English input was available for the young learners, only relatively little input was given to the adult learners, showing disparity of English inputs. In addition, the adult learners seem to lack a supportive setting where they could regularly utilise the target language (Clark and Clark 2019). Hence, there is a probability that if the older learners had access to sufficient English input and an enabling environment, an optimal learning outcome might have been recorded.
Similarly, participant I gave a descriptive analogy, relating language learning to other skills such as swimming. They argued that a child who starts learning how to swim has the tendency to master swimming skills better. These individuals may outperform an adult because learning new skills tend to be time consuming, and this time factor may not be favourable for an adult learner as adulthood comes with greater responsibilities which make learning more challenging.
In contrast, both participants SandJwere of the opinion that learning a second language could be possible irrespective of the age factor. The two crucial elements they both emphasised were learner commitment and interest in learning. With no opportunity to learn English at an earlier age, participant Jwas determined and eventually pursued a Masters-level degree abroad in a country where English is the primary language. This implies that adult learners who have a sense of dedication, devotion, and enthusiasm towards learning a target language can succeed in the learning process, their age notwithstanding. It also suggests that the learners’ commitment and passion towards the target language can enhance the learning process. This finding corroborates Singleton and Leśniewska’s (2021) opinion that the age factor should not be a benchmark, as some non-biological factors such as motivation, learning environment, exposure, and educational background also play vital roles in the learning process.
The success of participant J in learning a language later in life also challenges the assumption from Hartshorne et al. (2018) regarding the ‘critical period window’, suggesting that the maximum possible age the target language can be acquired successfully is 17, after which it might be impossible to learn the target language. Supporting J’s experiences, Singleton and Pfenninger (2018) asserted that adults tend to be more advantaged in second language learning since their maturity and already developed metalinguistic awareness of the first language might significantly enhance learning the target language. This maturity factor may give adult learners an edge over their young counterparts, especially in instructed learning contexts rather than in naturalistic learning, where young learners could be more advantaged (Hsiao and Oxford, 2022).
Conclusion
From the findings of this study, it can be concluded that although young learners of a second language might appear to learn more easily, since they are likely to learn naturally, adult learners may also be able to achieve this. Their developed metalinguistic capacity, intrinsic motivation, and maturity generally, if appropriately harnessed, can be an added advantage. In essence, without totally undermining the widely held belief of ‘the earlier the better’, while L2 teachers, policy makers, curriculum designers and educators generally ought to encourage starting L2 learning early, there should also be acknowledgement of the benefits of learning as an adult. Regardless of age factor, learners can thrive in the learning process if they have a sense of dedication, devotion, and enthusiasm towards learning the target language. Educators, language policy makers, curriculum and syllabus designers, language instructors, language students, and researchers who are interested in second language learning concerns, therefore, ought to be aware and take cognizance of the possible implications of both starting second language learning at an earlier and later age. This might both inform and influence their approach to language teaching and decision making generally.
Limitation of the study and recommendation
Due to the sample size of this study (being a small-scale study), the findings of this study could have limited generalizability. As emphasized by Collins and Munoz (2016), homogeneous sample size case studies centred on selected learners may lack a grounded representation of L2 learners’ broader population. It could, therefore, be difficult to draw generalized conclusions about the impact of age on second language learning as differences persist in educational background, cognitive and developmental variability, exposure to English, and socio-economic background of learners (Paradis, 2016; Collins and Munoz, 2016; Dekeyser, 2016). As an exploratory case study, this study centres on the age of second language learning, employing adult learners only as participants to identify patterns and validate arguments on the ideal age to learn an additional language, providing a basis for future and more detailed research. The age factor in second language learning could be investigated more thoroughly, employing a larger number of second language speakers of English, both children and adults from different linguistic backgrounds. It might be interesting to compare the effects of age disparities between children and adults on a large scale. A mixed methods research design may be more significant in this regard. This might enhance drawing both generalized and contextualized insights into how age factor influences the learning process.
References
Abdel Aal, A.M.A. (2016) ‘Delayed puberty’, Human Andrology, 6(2), pp. 27–30. doi:10.1097/01.xha.0000475202.35073.5f.
Abello-Contesse, C. (2008) ‘Age and the critical period hypothesis’, ELT Journal, 63(2), pp. 170–172. doi:10.1093/elt/ccn072.
Berko, G. and Bernstein, R. (2009) The Development of Language. Allyn & Bacon.
Bhardwaj, P. (2019) ‘Types of sampling in research’, Journal of the Practice of Cardiovascular Sciences, 5(3), p. 157. doi: 10.4103/jpcs.jpcs_62_19.
Bianco, S., Gasparini, F. and Schettini, R. (2019) ‘Color Coding for Data Visualization’, in Encyclopedia of Information Science and Technology, Third Edition, pp. 1682–1691. doi:10.4018/978-1-4666-5888-2.ch161.
Birdsong, D. (2018) Critical periods, in Aronoff, M. (ed.) Oxford Bibliographies in Linguistics. New York: Oxford University Press. Available at: https://www.oxfordbibliographies.com/view/document/obo-9780199772810/obo-9780199772810-0139.xml.
Biro, M., Bin, H., Halley, W., Catherine, M. and Susan, M. (2020) ‘Pubertal growth, IGF-1, and windows of susceptibility: Puberty and future breast cancer risk’, Journal of Adolescent Health, 68, pp. 517–522.
Birt, L., Scott, S., Cavers, D., Campbell, C. and Walter, F. (2016) ‘Member checking: A tool to enhance trustworthiness or merely a nod to validation?’, Qualitative Health Research, 26(13), pp. 1802–1811. doi:10.1177/1049732316654870.
Braun, V. and Clarke, V. (2013) Successful qualitative research: A practical guide for beginners. London: Sage.
Braun, V. and Clarke, V. (2020) ‘One size fits all? What counts as quality practice in (reflexive) thematic analysis?’, Qualitative Research in Psychology, 18(3), pp. 1–25.
Braun, V. and Clarke, V. (2021) Thematic Analysis. London: SAGE.
Candela, A.G. (2019) ‘Exploring the function of member checking’, The Qualitative Report, 24(3), pp. 619–628.
Chen, M.L. (2018) ‘A data-driven critical review of second language acquisition in the past 30 years’, Publications, 6(3), p. 33. doi:10.3390/publications6030033.
Chu, R.K. (2006) ‘An Interview with an English as a Second Language Learner: A Case Study of an Adult Chinese L1 Speaker’. Available at: https://www.academia.edu/29513246/_An_Interview_with_an_English_as_a_Second_Language_Learner_A_Case_Study_of_an_Adult_Chinese_L1_Speaker_
Clark, H. and Clark, E. (2019) Psychology and Language: An Introduction to Psycholinguistics. New York: Harcourt Brace Jovanovich.
Cohen, L., Manion, L. and Morrison, K. (2011) Research methods in education. London: Routledge.
Collins, L. and Muñoz, C. (2016) ‘The effectiveness of language learning in younger and older age groups’, Language Teaching, 49(1), pp. 161–176.
Creswell, J.W. (2009) Research design: qualitative, quantitative, and mixed methods approaches. New Delhi: Sage.
DeKeyser, R. (2016) ‘A critical review of age effects in L2 acquisition’, Language Learning, 66(S1), pp. 1–33.
Dollmann, J., Irena, K. and Markus, W. (2020) ‘Speaking accent-free in L2 beyond the critical period: The compensatory role of individual abilities and opportunity structures’, Applied Linguistics, 41, pp. 787–809.
Dornyei, Z. (2007). Research Methods in Applied Linguistics. Oxford: Oxford University Press.
Doughty, C. and Long, M.H. (2003) The handbook of second language acquisition. Malden, Ma: Blackwell Pub.
Flege, J.E. and Liu, S. (2000) ‘The critical period hypothesis and ultimate attainment in second language acquisition’, Studies in Second Language Acquisition, 22(4), pp. 527–552. doi: 10.1017/S0272263100004025.
Gass, S.M. and Selinker, L. (2008) Second language acquisition: An introductory course. New York: Routledge.
Gawi, E.M.K. (2012) ‘The effects of age on second language acquisition in a Saudi Arabian context: Early access to language learning’, International Journal of Applied Linguistics and English Literature, 1(6), pp. 123–130. Available at: https://doi.org/10.7575/ijalel.v.1n.6p.123.
Genesee, F. and Nicoladis, E. (2007) ‘Bilingual first language acquisition’, in Hoff, E. and Shatz, M. (eds.) Blackwell Handbook of Language Development, pp. 324–342. doi:10.1002/9780470757833.ch16.
Gunesekera, M. (2010) The postcolonial identity of Sri Lankan English (2nd ed.). Colombo: Vijitha Yapa Publications.
Hartshorne, J.K., Tenenbaum, J.B. and Pinker, S. (2018) ‘A critical period for second language acquisition: Evidence from 2/3 million English speakers’, Cognition, 177, pp. 263–277. doi:10.1016/j.cognition.2018.04.007.
Harvey, L. (2015) ‘Beyond member-checking: A dialogic approach to the research interview’, International Journal of Research & Method in Education, 38(1), pp. 23–38.
Hsiao, T. and Oxford, R.L. (2002) ‘Comparing theories of language learning strategies: A confirmatory factor analysis’, The Modern Language Journal, 86(3), pp. 368–383. doi:10.1111/1540-4781.00155.
Iwuchukwu, G.C.S. and Iwuchukwu, R.N. (2018) ‘Sociolinguistics and language education in Nigeria’, Global Journal of Social Sciences Studies, 4(1), pp. 13–22. doi:10.20448/807.4.1.13.22.
Kuhl, P.K. (2011) ‘Early language learning and the critical period’, Annual Review of Neuroscience, 34, pp. 219–243. Available at: https://doi.org/10.1146/annurev-neuro-060909-152330
Landow, G.P. (2013) The Medium of Instruction in Historical Contexts of Education. London: Routledge.
Leśniewska, J. (2021) ‘The Critical Period Hypothesis for L2 Acquisition: An Unfalsifiable Embarrassment?’, Languages, 6(3), p. 149. doi: 10.3390/languages6030149.
Lightbown, P.M. and Spada, N. (2013) How languages are learned. Oxford: Oxford University Press.
Liquin, E.G. and Gopnik, A. (2022) ‘Children are more exploratory and learn more than adults in an approach-avoid task’, Cognition, 218, p. 104940. doi:10.1016/j.cognition.2021.104940.
Long, M. (1990) ‘Maturational constraints on language development’, Studies in Second Language Acquisition, 12, pp. 251–285.
Marinova-Todd, S.H., Marshall, D.B. and Snow, C.E. (2000) ‘Three misconceptions about age and L2 learning’, TESOL Quarterly, 34(1), p. 9. doi:10.2307/3588095.
Meisel, J.M. (2016) ‘Early child second language acquisition: French gender in German children’, Bilingualism: Language and Cognition, 21(4), pp. 656–673. doi:10.1017/s1366728916000237.
Miyahara, M. (2020) ‘Sampling: problematizing the issue’, in McKinley, J. and Rose, H. (eds.) Routledge handbook of research methods in applied linguistics. London: Routledge.
Muñoz, C. (2001) ‘Factores escolares e individuales en el aprendizaje formal de un idioma extranjero’, ELUA. Estudios de Lingüística Universidad de Alicante, Anexo 1, pp. 249–270.
Ortega, L. (2009) Understanding Second Language Acquisition. London: Hodder Education.
Paradis, J. (2016) ‘L2 acquisition in children: The role of input, cognitive development, and linguistic factors’, Applied Linguistics, 37(4), pp. 583–588.
Pfenninger, S.E. and Singleton, D. (2017) Beyond age effects in instructional L2 learning: Revisiting the age factor. Bristol: Multilingual Matters.
Pfenninger, S.E. and Singleton, D. (2018) ‘Starting age overshadowed: The primacy of differential environmental and input effects on L2 attainment in an instructional context’, Language Learning, 68, pp. 410–443. doi:10.1111/lang.12318.
Pfenninger, S.E. and Singleton, D. (2019) ‘A critical review of research relating to the learning, use and effects of additional and multiple languages in later life’, Language Teaching, 52(4), pp. 419–449. doi:10.1017/S0261444819000235.
Roberts, K., Dowell, A., and Nie, J.B. (2019) ‘Attempting rigour and replicability in thematic analysis of qualitative research: A case study of codebook development’, BMC Medical Research Methodology, 19, 66. doi: 10.1186/s12874-019-0707-y.
Sarantakos, S. (2013) Social research. New York: Palgrave Macmillan.
Scovel, T. (2000) ‘A critical review of the Critical Period Hypothesis’, Annual Review of Applied Linguistics, 20, pp. 213–223.
Sherif (2019) History of Education in Nigeria – Development Since 1960 Till Date & Before Independence. Information [online]. Available at: https://naijaquest.com/history-of-education-in-nigeria/
Singleton, D.M. and Ryan, L. (2004) Language acquisition: the age factor. Clevedon: Multilingual Matters.
Singleton, D. and Leśniewska, J. (2021) ‘The Critical Period Hypothesis for L2 Acquisition: An Unfalsifiable Embarrassment?’, Languages, 6(3), p. 149. doi:10.3390/languages6030149.
Tomasello, M. (2003) Constructing a language: A usage-based theory of language acquisition. Cambridge, MA: Harvard University Press.
Walker, I. (2010) Research methods and statistics. Basingstoke: Palgrave Macmillan.
Wijayatunga, A. (2018) ‘English as a medium of instruction in secondary schools in Sri Lanka: challenges’, International Conference on Education. doi:10.17501/icedu.2018.4117.