The field of psycholinguistics, or the psychology of language, works to understand the psychological and neurobiological factors that allow humans to use, produce, comprehend, and acquire language. Focusing on the subject of language acquisition, or the process in which humans acquire the ability to use and comprehend language, one researcher named Eric Lenneberg pioneered the critical period hypothesis (Gillespie, 2017). In this popular and much debated hypothesis, it is argued that the basic elements of language must be acquired before adolescence in order to become a fully native user of a certain language. Although this hypothesis has been used to explore why language deficits occur for children who lived in isolation from human contact, this hypothesis also can be looked at in terms of how to best acquire a second language. This paper will explore research conducted on the critical period hypothesis in relation to second language acquisition, and it will explore research on other factors that affect second language acquisition.

In general, there are various approaches to learning a second language—whether that includes using an online language-learning platform such as Duolingo or whether that includes learning a second language in the classroom. When it comes to learning a second language in the classroom, second language learning is often required throughout middle and high school, and becomes more optional during higher education. Although there are various approaches to learning a second language, only about 20% of people in the United States are bilingual (Grosjean, 2012). Given the fact that exposure to and teachings of second languages are prominent throughout the United States; does the low percentage of bilinguals in the U.S. reflect support for the critical period hypothesis? Perhaps more people in the U.S. have a basic understanding for second languages, but are unable to become similar to a fully native speaker because they did not fully acquire the elements of a given language before adolescence. In order to address these questions, the research of Johnson and Newport (1989), Brice and Brice (2008), and Strid (2017) will be explored.

The research conducted on the topic of the critical period hypothesis in relation to second language acquisition reveal differing findings throughout the years. In the Johnson and Newport (1989) study, the researchers found evidence in support of the critical period hypothesis in relation to second language acquisition. Support for the critical period hypothesis, in this study, was found through examining English proficiency levels of 46 native Korean or Chinese speakers who arrived in the United States between the ages of three and 39 years-old. In order to test the English proficiency levels of the different-aged participants, the researchers did two things. First, Johnson and Newport (1989) split the 46 participants into two groups: people who came to the United States before the age of 15 and people who came to the United States after the age of 17. Furthermore, Johnson and Newport (1989) tested the two groups of participants on their ability to judge the grammaticality of various, spoken English sentences. In this study, judging grammaticality refers to the ability of the participants to understand if the English sentences were produced in agreement with the rules of grammar. As found by Johnson and Newport (1989), a strong relationship exists between age of arrival in the United States and performance on the grammaticality judgment tasks. Those who came to the U.S. at an earlier age, and thus were exposed to English at an earlier age, obtained higher test scores than those who came to the U.S. after puberty. In fact, Johnson and Newport (1989) specifically note that fully achieving native fluency in a language is possible if immersed in the language before the age of seven—and that later immersion in a language results in a decreased ability to become a fully native speaker.

Although Johnson and Newport (1989) found evidence in support of the critical period hypothesis, Brice and Brice (2008) found evidence that opposes the hypothesis. In their study, Brice and Brice (2008) tested different age groups of Spanish-English bilinguals in their ability to perceive aspects of the English language, and compared their abilities to English monolinguals. The measuring of speech perception in this study refers to the extent to which the participants heard, interpreted, and understood the sounds of the English language that they heard. Essentially, Brice and Brice (2008) found that exposure to a second language over a period of six years or more can result in increased abilities in that second language. However, Brice and Brice (2008) also found that the ultimate ability to reach high levels of proficiency in second languages occurred when the age of arrival to the United States was between nine and fifteen-years-old. Unlike what is hypothesized in the critical period hypothesis, the participants who arrived to the U.S. and thus were exposed to English for the first time between nine and fifteen years of age were able to become similar to native speakers in English. These participants did not master English before puberty, but were still able to reach high levels of proficiency in the language.

Although Johnson and Newport (1989) and Brice and Brice (2008) came to different conclusions regarding the existence of a critical period for learning languages, Strid (2017) came to a conclusion that is almost a compromise between the two studies. After examining and exploring various research studies regarding the critical period hypothesis and second language acquisition, Strid (2017) asserted that the critical period is not completely proven and that evidence instead points to a sensitive period. Instead of a critical period for language acquisition, a sensitive period asserts that lack of exposure to language can affect a person’s acquisition of the language—but that lack of acquisition can be fixed and reversed with exposure to and practice of the language. The research conducted by Strid (2017) also suggests that the low percentage of bilingualism in the U.S. could be a result of the manner in which language is presented within the U.S. school curriculum. Although some classes in U.S. schools are dedicated to second language learning, Strid (2017) argued that the curriculum is not adequate or lengthy enough to foster complete competence in another language. Essentially, Strid (2017) asserted that the critical language hypothesis can be harmful—as there are many other factors that influence second language acquisition that do not involve having to master a language before puberty.

As Strid (2017) suggested, there are various factors that influence second language acquisition—and these factors can range from the biological to the surprising and to the more expected. In the study conducted by Yang, Gates, Molenaar, and Li (2015), the researchers conducted functional magnetic resonance imaging (fMRI) tests in order to examine the neurological activities associated with learning a second language. The participants in the study were all native English speakers, who were separated into two groups: learners of Chinese and non-learners. The learners of Chinese group went through 18 training sessions in order to learn 48 Chinese pseudowords—or non-words that appear to be actual words in a certain language. After six weeks, both groups were given fMRI tests. In regard to differences between the learner and non-learner group, Yang et al. (2015) found that the two groups rely on different patterns of brain activation. For example, the learner group showed increased activation in a part of the brain known as the angular gyrus—which is involved in tasks associated with word reading, number and word meaning processing, and memory retrieval. Furthermore, Yang et al. (2015) found that the more successful learners within the learner group demonstrated higher activation in the language-related parts of the brain when compared to the less successful learners. In sum, the study conducted by Yang et al. (2015) demonstrates that there is a biological component to second language acquisition. When learning a second language, people may be more or less successful in their efforts due to changes in brain networks and activation levels.

Moving away from the biological factors that influence successful second language acquisition, Kang and Williamson (2014) examined the role of background music on second language learning. In their study, Kang and Williamson (2014) allowed participants to take a beginners’ CD-based course in either Mandarin Chinese or in Arabic that either contained background music or that did not contain background music. Interestingly, the presence of music within the CD-based course significantly improved the participants’ performance on recalling Mandarin Chinese words and translating Mandarin Chinese. The same effect was not found for the participants learning Arabic; however, the researchers noted that this finding may be due to the fact that the participants learning Arabic performed significantly worse than the other participants to begin with. The Kang and Williamson (2014) study suggests that when learning a second language, background music can positively supplement and strengthen memory for learning materials.

Relating back to the study conducted by Strid (2017) is the study conducted by Freed, Segalowitz, and Dewey (2004). As Strid (2017) asserted, the classroom setting for learning a second language is often not adequate or comprehensive enough for second language acquisition—and Freed et al. (2004) corroborated this assertion. In their study, Freed et al. (2004) measured the levels of fluency and acquisition in French attained by different groups of college students. The groups in the study were students learning French in the following contexts: in formal language classrooms at their university, in an intensive summer immersion program, and in a study abroad setting. Students learning French in a classroom received 12 weeks of instruction, for about 3-4 hours a week. Students learning French in the immersion program received 7 weeks of instruction, spent 3-4 hours a day in the classroom, and were required to use only French during the program. Finally, students abroad studied French in Paris for 12 weeks and spent approximately 2-5 hours in the classroom learning French. To measure the oral fluency of the students, Freed et al. (2004) conducted tests to assess the students’ ability to speak well, without hesitations, repetitions, grammar issues, and more. Freed et al. (2004) also assessed the words per minute, in French, that the students were able to say. Essentially, Freed et al. (2004) found that students learning French in the traditional classroom made no significant gains in terms of their fluency. However, students in the study abroad setting and the immersion setting especially made gains in terms of their rate, quantity, quality, and smoothness of their speech in French. In fact, students in the immersion setting were most easily able to acquire fluency. The results of the Freed et al. (2004) study illustrate that type of learning influences second language acquisition—and that the quality of the learning context and efforts to use a second language make a differences in terms of gaining second language abilities.

To conclude, there exists a great deal of research concerning the factors that influence second language acquisition. Although research concerning the critical period hypothesis in relation to second language acquisition is mixed, the hypothesis is nonetheless influential and important to delving into what does affect second language acquisition. After exploring various research studies on the topic of learning a second language, successfully learning a second language can be facilitated by changes in brain networks, listening to music, being immersed in the second language, and perhaps even by being introduced to the language during adolescence. The various studies conducted on the topic of second language acquisition are of extreme importance, as these studies can influence the success rates of people learning a second language.

References

Brice, A. E., & Brice, R. (2008). Examination of the critical period hypothesis and ultimate attainment among Spanish-English bilinguals and English-speaking monolinguals. Asia Pacific Journal of Speech, Language, and Hearing, 11(3), 143-160. doi:10.1179/136132808805297188

Freed, B. F., Segalowitz, N., & Dewey, D. P. (2004). Context of learning and second language fluency in French: Comparing regular classroom, study abroad, and intensive domestic immersion programs. Studies in Second Language Acquisition, 26(2), 275-301. doi:10.1017/S0272263104262064

Gillespie, M. (2017). Language acquisition [PDF document]. Retrieved from https://mycourses.unh.edu/courses/32934/files/1370238?module_item_id=483158

Grosjean, F. (2012, May 20). Bilinguals in the United States. Retrieved from https://www.psychologytoday.com/blog/life-bilingual/201205/bilinguals-in-the-united-states

Johnson, J. S., & Newport, E. L. (1989). Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology, 21(1), 60-99. doi:10.1016/0010-0285(89)90003-0

Kang, H. J., & Williamson, V. J. (2014). Background music can aid second language learning. Psychology of Music, 42(5), 728-747. doi:10.1177/0305735613485152

Strid, J. E. (2017). The Myth of the Critical Period. TESOL Journal, 8(3), 700-715. doi:10.1002/tesj.296

Yang, J., Gates, K. M., Molenaar, P., & Li, P. (2015). Neural changes underlying successful second language word learning: An fMRI study. Journal of Neurolinguistics, 33, 29-49. doi:10.1016/j.jneuroling.2014.09.004