Second-language acquisition, second-language learning, or L2 acquisition, is the process by which people learn a second language. Second-language acquisition (often abbreviated to SLA) also refers to the scientific discipline devoted to studying that process. Second language refers to any language learned in addition to a person's first language; although the concept is named second-language acquisition, it can also incorporate the learning of third, fourth, or subsequent languages. Second-language acquisition refers to what learners do; it does not refer to practices in language teaching.
- 1 Outline
- 2 Stages
- 3 Comparisons with first-language acquisition
- 4 Learner language
- 5 Language transfer
- 6 Input and interaction
- 7 Cognitive factors
- 8 Sociocultural factors
- 9 Linguistic factors
- 10 Individual variation
- 11 Classroom second-language acquisition
- 12 See also
- 13 Notes
- 14 References
- 15 Further reading
- 16 External links
The academic discipline of second-language acquisition is a subdiscipline of applied linguistics. It is broad-based and relatively new. As well as the various branches of linguistics, second-language acquisition is also closely related to psychology, cognitive psychology, and education. To separate the academic discipline from the learning process itself, the terms second-language acquisition research, second-language studies, and second-language acquisition studies are also used.
SLA research began as an interdisciplinary field, and because of this it is difficult to identify a precise starting date. However, two papers in particular are seen as instrumental to the development of the modern study of SLA: Pit Corder's 1967 essay The Significance of Learners' Errors, and Larry Selinker's 1972 article Interlanguage. The field saw a great deal of development in the following decades. By the year 2010, second-language acquisition was studied from a wide variety of disciplinary perspectives, and there was a proliferation of different theories. However, the main two approaches were linguistic theories based upon Noam Chomsky's universal grammar, and psychological theories such as skill acquisition theory and connectionism.
The term acquisition was originally used to emphasize the subconscious nature of the learning process, but in recent years learning and acquisition have become largely synonymous.
Second-language acquisition can incorporate heritage language learning, but it does not usually incorporate bilingualism. Most SLA researchers see bilingualism as being the end result of learning a language, not the process itself, and see the term as referring to native-like fluency. Writers in fields such as education and psychology, however, often use bilingualism loosely to refer to all forms of multilingualism. Second-language acquisition is also not to be contrasted with the acquisition of a foreign language; rather, the learning of second languages and the learning of foreign languages involve the same fundamental processes in different situations.
There has been much debate about exactly how language is learned, and many issues are still unresolved. There are many theories of second-language acquisition, but none are accepted as a complete explanation by all SLA researchers. Due to the interdisciplinary nature of the field of second-language acquisition, this is not expected to happen in the foreseeable future.
Second-language acquisition can be divided up into five stages: preproduction, early production, speech emergence, intermediate fluency, and advanced fluency. The first stage is preproduction, also known as the silent period. Learners at this stage have a receptive vocabulary of up to 500 words, but they do not yet speak their second language. Not all learners go through a silent period. Some learners start speaking straight away, although their output may consist of imitation rather than creative language use. Others may be required to speak from the start as part of a language course. For learners that do go through a silent period, it may last around three to six months.
The second stage of acquisition is early production, during which learners are able to speak in short phrases of one or two words. They can also memorize chunks of language, although they may make mistakes when using them. Learners typically have both an active and receptive vocabulary of around 1000 words. This stage normally lasts for around six months.
The third stage is speech emergence. Learners' vocabularies increase to around 3000 words during this stage, and they can communicate using simple questions and phrases. They may often make grammatical errors. The stage after speech emergence is intermediate fluency. At this stage, learners have a vocabulary of around 6000 words, and can use more complicated sentence structures. They are also able to share their thoughts and opinions. Learners may make frequent errors with more complicated sentence structures. The final stage is advanced fluency, which is typically reached somewhere between five and ten years of learning the language. Learners at this stage can function at a level close to native speakers.
The time taken to reach a high level of proficiency can vary depending on the language learned. In the case of native English speakers, some estimates were provided by the Foreign Service Institute (FSI) of the U.S. Department of State, which compiled approximate learning expectations for a number of languages for their professional staff (native English speakers who generally already know other languages). Of the 63 languages analyzed, the five most difficult languages to reach proficiency in speaking and reading, requiring 88 weeks (2200 class hours), are Arabic, Cantonese, Mandarin, Japanese, and Korean. The Foreign Service Institute and the National Virtual Translation Center both note that Japanese is typically more difficult to learn than other languages in this group.
Comparisons with first-language acquisition
Adults who learn a second language differ from children learning their first language in a number of ways. One of the most striking of these is that very few adult second-language learners reach the same competence as native speakers of that language. Children learning a second language are more likely to achieve native-like fluency than adults, but in general it is very rare for someone speaking a second language to pass completely for a native speaker. When a learner's speech plateaus in this way it is known as fossilization.
In addition, some errors that second-language learners make in their speech originate in their first language. For example, Spanish speakers learning English may say "Is raining" rather than "It is raining", leaving out the subject of the sentence. French speakers learning English, however, do not usually make the same mistake. This is because sentence subjects can be left out in Spanish, but not in French. This kind of influence of the first language on the second is known as negative language transfer.
Also, when people learn a second language, the way they speak their first language changes in subtle ways. These changes can be with any aspect of language, from pronunciation and syntax to gestures the learner makes and the things they tend to notice. For example, French speakers who spoke English as a second language pronounced the /t/ sound in French differently from monolingual French speakers. This kind of change in pronunciation has been found even at the onset of second-language acquisition; for example, English speakers pronounced the English /p t k/ sounds, as well as English vowels, differently after they began to learn Korean. These effects of the second language on the first led Vivian Cook to propose the idea of multi-competence, which sees the different languages a person speaks not as separate systems, but as related systems in their mind.
Learner language is the written or spoken language produced by a learner. It is also the main type of data used in second-language acquisition research. Much research in second-language acquisition is concerned with the internal representations of a language in the mind of the learner, and in how those representations change over time. It is not yet possible to inspect these representations directly with brain scans or similar techniques, so SLA researchers are forced to make inferences about these rules from learners' speech or writing.
Originally, attempts to describe learner language were based on comparing different languages and on analyzing learners' errors. However, these approaches weren't able to predict all the errors that learners made when in the process of learning a second language. For example, Serbo-Croat speakers learning English may say "What does Pat doing now?", although this is not a valid sentence in either language.
To explain this kind of systematic error, the idea of the interlanguage was developed. An interlanguage is an emerging language system in the mind of a second-language learner. A learner's interlanguage is not a deficient version of the language being learned filled with random errors, nor is it a language purely based on errors introduced from the learner's first language. Rather, it is a language in its own right, with its own systematic rules. It is possible to view most aspects of language from an interlanguage perspective, including grammar, phonology, lexicon, and pragmatics.
There are three different processes that influence the creation of interlanguages:
- Language transfer. Learners fall back on their mother tongue to help create their language system. Transfer can be positive, i.e. promote learning, or negative, i.e. lead to mistakes. In the latter case, linguists also use the term interference error.
- Overgeneralization. Learners use rules from the second language in roughly the same way that children overgeneralise in their first language. For example, a learner may say "I goed home", overgeneralizing the English rule of adding -ed to create past tense verb forms. English children also produce forms like goed, sticked, bringed. German children equally overextend regular past tense forms to irregular forms.
- Simplification. Learners use a highly simplified form of language, similar to speech by children or in pidgins. This may be related to linguistic universals.
The concept of interlanguage has become very widespread in SLA research, and is often a basic assumption made by researchers.
Sequences of acquisition
|1.||Plural -s||Girls go.|
|2.||Progressive -ing||Girls going.|
|3.||Copula forms of be||Girls are here.|
|4.||Auxiliary forms of be||Girls are going.|
|5.||Definite and indefinite
articles the and a
|The girls go.|
|6.||Irregular past tense||The girls went.|
|7.||Third person -s||The girl goes.|
|8.||Possessive 's||The girl's book.|
|A typical order of acquisition for English, according to Vivian Cook's 2008 book Second Language Learning and Language Teaching.|
In the 1970s several studies investigated the order in which learners acquired different grammatical structures. These studies showed that there was little change in this order among learners with different first languages. Furthermore, it showed that the order was the same for adults and children, and that it did not even change if the learner had language lessons. This supported the idea that there were factors other than language transfer involved in learning second languages, and was a strong confirmation of the concept of interlanguage.
However, the studies did not find that the orders were exactly the same. Although there were remarkable similarities in the order in which all learners learned second-language grammar, there were still some differences among individuals and among learners with different first languages. It is also difficult to tell when exactly a grammatical structure has been learned, as learners may use structures correctly in some situations but not in others. Thus it is more accurate to speak of sequences of acquisition, where particular grammatical features in a language have a fixed sequence of development, but the overall order of acquisition is less rigid.
Although second-language acquisition proceeds in discrete sequences, it does not progress from one step of a sequence to the next in an orderly fashion. There can be considerable variability in features of learners' interlanguage while progressing from one stage to the next. For example, in one study by Rod Ellis a learner used both "No look my card" and "Don't look my card" while playing a game of bingo. A small fraction of variation in interlanguage is free variation, when the learner uses two forms interchangeably. However, most variation is systemic variation, variation which depends on the context of utterances the learner makes. Forms can vary depending on linguistic context, such as whether the subject of a sentence is a pronoun or a noun; they can vary depending on social context, such as using formal expressions with superiors and informal expressions with friends; and also, they can vary depending on psycholinguistic context, or in other words, on whether learners have the chance to plan what they are going to say. The causes of variability are a matter of great debate among SLA researchers.
Some researchers, like A. Z. Guirora, argue that the hardest part of learning a new language is pronunciation, which can result in a "foreign accent". There is a view by some that accents are caused by transfer between the sounds of the first and second languages, for which there are three possibilities:
- One or more phonemes of the second language are not found in the learner's native language at all. For example, Korean does not have any phonemes corresponding to the English phonemes /f/ or /v/, so they would be completely new to Korean learners of English.
- The first language has one of the two contrasting phonemes. For example, Japanese has a /p/ sound as in the English paid, but no /f/ sound as in the English fade. Japanese learners of English need to learn a new phoneme.
- The second language phonemes both exist in the native language, but as allophones of the same phoneme. For example, in Japanese, [l] and [r] are allophones so Japanese learners of English need to learn to distinguish these sounds.
Totally new sounds do not always pose significant problems for second-language learners, unless they are radically outside the classes of sound in the native language. The most difficult phoneme pairs to learn are often allophones of the same phoneme, as in Japanese learning to distinguish between /l/ and /r/.
One important difference between first-language acquisition and second-language acquisition is that the process of second-language acquisition is influenced by languages that the learner already knows. This influence is known as language transfer. Language transfer is a complex phenomenon resulting from interaction between learners’ prior linguistic knowledge, the target-language input they encounter, and their cognitive processes. Language transfer is not always from the learner’s native language; it can also be from a second language, or a third. Neither is it limited to any particular domain of language; language transfer can occur in grammar, pronunciation, vocabulary, discourse, and reading.
One situation in which language transfer often occurs is when learners sense a similarity between a feature of a language that they already know and a corresponding feature of the interlanguage they have developed. If this happens, the acquisition of more complicated language forms may be delayed in favor of simpler language forms that resemble those of the language the learner is familiar with. Learners may also decline to use some language forms at all if they are perceived as being too distant from their first language.
Language transfer has been the subject of several studies, and many aspects of it remain unexplained. Various hypotheses have been proposed to explain language transfer, but there is no single widely accepted explanation of why it occurs.
Input and interaction
The primary factor affecting language acquisition appears to be the input that the learner receives. Stephen Krashen took a very strong position on the importance of input, asserting that comprehensible input is all that is necessary for second-language acquisition. Krashen pointed to studies showing that the length of time a person stays in a foreign country is closely linked with his level of language acquisition. Further evidence for input comes from studies on reading: large amounts of free voluntary reading have a significant positive effect on learners' vocabulary, grammar, and writing. Input is also the mechanism by which people learn languages according to the universal grammar model.
The type of input may also be important. One tenet of Krashen's theory is that input should not be grammatically sequenced. He claims that such sequencing, as found in language classrooms where lessons involve practicing a "structure of the day", is not necessary, and may even be harmful.
While input is of vital importance, Krashen's assertion that only input matters in second-language acquisition has been contradicted by more recent research. For example, students enrolled in French-language immersion programs in Canada still produced non-native-like grammar when they spoke, even though they had years of meaning-focused lessons and their listening skills were statistically native-level. Output appears to play an important role, and among other things, can help provide learners with feedback, make them concentrate on the form of what they are saying, and help them to automatize their language knowledge. These processes have been codified in the theory of comprehensible output.
Researchers have also pointed to interaction in the second language as being important for acquisition. According to Long's interaction hypothesis the conditions for acquisition are especially good when interacting in the second language; specifically, conditions are good when a breakdown in communication occurs and learners must negotiate for meaning. The modifications to speech arising from interactions like this help make input more comprehensible, provide feedback to the learner, and push learners to modify their speech.
Much modern research in second-language acquisition has taken a cognitive approach. Cognitive research is concerned with the mental processes involved in language acquisition, and how they can explain the nature of learners' language knowledge. This area of research is based in the more general area of cognitive science, and uses many concepts and models used in more general cognitive theories of learning. As such, cognitive theories view second-language acquisition as a special case of more general learning mechanisms in the brain. This puts them in direct contrast with linguistic theories, which posit that language acquisition uses a unique process different from other types of learning.
The dominant model in cognitive approaches to second-language acquisition, and indeed in all second-language acquisition research, is the computational model. The computational model involves three stages. In the first stage, learners retain certain features of the language input in short-term memory. (This retained input is known as intake.) Then, learners convert some of this intake into second-language knowledge, which is stored in long-term memory. Finally, learners use this second-language knowledge to produce spoken output. Cognitive theories attempt to codify both the nature of the mental representations of intake and language knowledge, and the mental processes which underlie these stages.
In the early days of second-language acquisition research interlanguage was seen as the basic representation of second-language knowledge; however, more recent research has taken a number of different approaches in characterizing the mental representation of language knowledge. There are theories that hypothesize that learner language is inherently variable, and there is the functionalist perspective that sees acquisition of language as intimately tied to the function it provides. Some researchers make the distinction between implicit and explicit language knowledge, and some between declarative and procedural language knowledge. There have also been approaches that argue for a dual-mode system in which some language knowledge is stored as rules, and other language knowledge as items.
The mental processes that underlie second-language acquisition can be broken down into micro-processes and macro-processes. Micro-processes include attention; working memory; integration and restructuring, the process by which learners change their interlanguage systems; and monitoring, the conscious attending of learners to their own language output. Macro-processes include the distinction between intentional learning and incidental learning; and also the distinction between explicit and implicit learning. Some of the notable cognitive theories of second-language acquisition include the nativization model, the multidimensional model and processability theory, emergentist models, the competition model, and skill-acquisition theories.
Other cognitive approaches have looked at learners' speech production, particularly learners' speech planning and communication strategies. Speech planning can have an effect on learners' spoken output, and research in this area has focused on how planning affects three aspects of speech: complexity, accuracy, and fluency. Of these three, planning effects on fluency has had the most research attention. Communication strategies are conscious strategies that learners employ to get around any instances of communication breakdown they may experience. Their effect on second-language acquisition is unclear, with some researchers claiming they help it, and others claiming the opposite.
Although the dominant perspective in second-language research is a cognitive one, from the early days of the discipline researchers have also acknowledged that social aspects play an important role. There have been many different approaches to sociolinguistic study of second-language acquisition, and indeed, according to Rod Ellis, this plurality has meant that "sociolinguistic SLA is replete with a bewildering set of terms referring to the social aspects of L2 acquisition". Common to each of these approaches, however, is a rejection of language as a purely psychological phenomenon; instead, sociolinguistic research views the social context in which language is learned as essential for a proper understanding of the acquisition process.
Ellis identifies three types of social structure which can affect the acquisition of second languages: sociolinguistic setting, specific social factors, and situational factors. Socialinguistic setting refers to the role of the second language in society, such as whether it is spoken by a majority or a minority of the population, whether its use is widespread or restricted to a few functional roles, or whether the society is predominantly bilingual or monolingual. Ellis also includes the distinction of whether the second language is learned in a natural or an educational setting. Specific social factors that can affect second-language acquisition include age, gender, social class, and ethnic identity, with ethnic identity being the one that has received most research attention. Situational factors are those which vary between each social interaction. For example, a learner may use more polite language when talking to someone of higher social status, but more informal language when talking with friends.
There have been several models developed to explain social effects on language acquisition. Schumann's Acculturation Model proposes that learners' rate of development and ultimate level of language achievement is a function of the "social distance" and the "psychological distance" between learners and the second-language community. In Schumann's model the social factors are most important, but the degree to which learners are comfortable with learning the second language also plays a role. Another sociolinguistic model is Gardner's socio-educational model, which was designed to explain classroom language acquisition. The inter-group model proposes "ethnolinguistic vitality" as a key construct for second-language acquisition. Language socialization is an approach with the premise that "linguistic and cultural knowledge are constructed through each other", and saw increased attention after the year 2000. Finally, Norton's theory of social identity is an attempt to codify the relationship between power, identity, and language acquisition.
A related but subtly different approach is taken in the sociocultural theory developed by Lev Vygotsky and his followers. While still essentially being based in the cognitive tradition, sociocultural theory has a fundamentally different set of assumptions to approaches to second-language acquisition based on the computational model. Furthermore, although it is closely affiliated with other social approaches, it is a theory of mind and not of general social explanations of language acquisition. According to Ellis, "It is important to recognize... that this paradigm, despite the label 'sociocultural' does not seek to explain how learners acquire the cultural values of the L2 but rather how knowledge of an L2 is internalized through experiences of a sociocultural nature."
Linguistic approaches to explaining second-language acquisition spring from the wider study of linguistics. They differ from cognitive approaches and sociocultural approaches in that they consider language knowledge to be unique and distinct from any other type of knowledge. The linguistic research tradition in second-language acquisition has developed in relative isolation from the cognitive and sociocultural research traditions, and as of 2010 the influence from the wider field of linguistics was still strong. Two main strands of research can be identified in the linguistic tradition: approaches informed by universal grammar, and typological approaches.
Typological universals are principles that hold for all the world's languages. They are found empirically, by surveying different languages and deducing which aspects of them could be universal; these aspects are then checked against other languages to verify the findings. The interlanguages of second-language learners have been shown to obey typological universals, and some researchers have suggested that typological universals may constrain interlanguage development.
The theory of universal grammar was proposed by Noam Chomsky in the 1950s, and has enjoyed considerable popularity in the field of linguistics. It focuses on describing the linguistic competence of an individual, as opposed to mechanisms of learning. It consists of a set of principles, which are universal and constant, and a set of parameters, which can be set differently for different languages. The "universals" in universal grammar differ from typological universals in that they are a mental construct derived by researchers, whereas typological universals are readily verifiable by data from world languages. It is widely accepted among researchers in the universal grammar framework that all first-language learners have access to universal grammar; this is not the case for second-language learners, however, and much research in the context of second-language acquisition has focused on what level of access learners may have.
There is considerable variation in the rate at which people learn second languages, and in the language level that they ultimately reach. Some learners learn quickly and reach a near-native level of competence, but others learn slowly and get stuck at relatively early stages of acquisition, despite living in the country where the language is spoken for several years. The reason for this disparity was first addressed with the study of language learning aptitude in the 1950s, and later with the good language learner studies in the 1970s. More recently research has focused on a number of different factors that affect individuals' language learning, in particular strategy use, social and societal influences, personality, motivation, and anxiety. The relationship between age and the ability to learn languages has also been a subject of long-standing debate.
The issue of age was first addressed with the critical period hypothesis. The strict version of this hypothesis states that there is a cut-off age at about 12, after which learners lose the ability to fully learn a language. This strict version has since been rejected for second-language acquisition, as adult learners have been observed who reach native-like levels of pronunciation and general fluency. However, in general, adult learners of a second-language rarely achieve the native-like fluency that children display, despite often progressing faster in the initial stages. This has led to speculation that age is indirectly related to other, more central factors that affect language learning.
There has been considerable attention paid to the strategies which learners use when learning a second language. Strategies have been found to be of critical importance, so much so that strategic competence has been suggested as a major component of communicative competence. Strategies are commonly divided into learning strategies and communicative strategies, although there are other ways of categorizing them. Learning strategies are techniques used to improve learning, such as mnemonics or using a dictionary. Communicative strategies are strategies a learner uses to convey meaning even when she doesn't have access to the correct form, such as using pro-forms like thing, or using non-verbal means such as gestures.
The learner's attitude to the learning process has also been identified as being critically important to second-language acquisition. Anxiety in language-learning situations has been almost unanimously shown to be detrimental to successful learning. A related factor, personality, has also received attention. There has been discussion about the effects of extravert and introvert personalities. However, one study has found that there were no significant differences between extraverts and introverts on the way they achieve success in a second language.
Social attitudes such as gender roles and community views toward language learning have also proven critical. Language learning can be severely hampered by cultural attitudes, with a frequently cited example being the difficulty of Navajo children in learning English. Also, the motivation of the individual learner is of vital importance to the success of language learning. Studies have consistently shown that intrinsic motivation, or a genuine interest in the language itself, is more effective over the long-term than extrinsic motivation, as in learning a language for a reward such as high grades or praise.
Classroom second-language acquisition
While the majority of SLA research has been devoted to language learning in a natural setting, there have also been efforts made to investigate second-language acquisition in the classroom. This kind of research has a significant overlap with language education, but it is always empirical, based on data and statistics, and it is mainly concerned with the effect that instruction has on the learner, rather than what the teacher does.
The research has been wide-ranging. There have been attempts made to systematically measure the effectiveness of language teaching practices for every level of language, from phonetics to pragmatics, and for almost every current teaching methodology. This research has indicated that many traditional language-teaching techniques are extremely inefficient. cited in Ellis 1994 It is generally agreed that pedagogy restricted to teaching grammar rules and vocabulary lists does not give students the ability to use the L2 with accuracy and fluency. Rather, to become proficient in the second language, the learner must be given opportunities to use it for communicative purposes.
Another area of research has been on the effects of corrective feedback in assisting learners.This has been shown to vary depending on the technique used to make the correction, and the overall focus of the classroom, whether on formal accuracy or on communication of meaningful content. There is also considerable interest in supplementing published research with approaches that engage language teachers in action research on learner language in their own classrooms. As teachers become aware of the features of learner language produced by their students, they can refine their pedagogical intervention to maximize interlanguage development.
- Bilingualism (neurology)
- International auxiliary language
- Language learning aptitude
- Neurolinguistic approach to second- language acquisition
- Language acquisition
- Language complexity
- List of language acquisition researchers
- Second-language attrition
- VanPatten & Benati 2010, pp. 2–5.
- Krashen (1982) made a sharp distinction between learning and acquisition, using learning to refer to the conscious aspects of the language learning process and acquisition to refer to the subconscious aspects. This strict separation of learning and acquisition is widely regarded as an oversimplification by researchers today, but his hypotheses were very influential and the name has stuck.
- Ellis 1997, p. 3.
- Haynes 2007, pp. 29–35.
- Ellis 2008, pp. 73–75.
- "Language Learning Difficulty for English Speakers". Zidbits. Retrieved 10 June 2012.
- "What's the Hardest Language to Learn?". Live Science. Livescience. Retrieved 10 June 2010.
- Cook 2008, p. 13.
- Cook 2008, p. 232.
- Flege 1987.
- Chang 2012.
- Cook 2008, p. 15.
- Ellis & Barkhuizen 2005, p. 4.
- Ellis & Barkhuizen 2005, p. 6.
- Mason, Timothy. "Didactics – 7 : Critique of Krashen III. Natural Order Hypothesis (2) :Interlanguage". Lecture in the didactics of English, Université of Versailles St. Quentin, a course run from 1993 to 2002. Retrieved 2011-02-10.
- Cook 2008, pp. 26–27.
- These studies were based on work by Brown (1973) on child first-language acquisition. The first such studies on child second-language acquisition were carried out by Dulay and Burt (1973, 1974a, 1974b, 1975). Bailey, Madden & Krashen (1974) investigated the order of acquisition among adult second-language learners. See Krashen (1977) for a review of these studies.
- Ellis 1997, pp. 25–29.
- VanPatten & Benati 2010, p. 166.
- Guirora, A.Z. (2006). "Empathy and second language learning". In Language Learning. 22(1). However, others like Piers Messum in Autonomy As Soon As Possible, maintain that pronunciation problems may be remedied if an appropriate approach is used.
- Eckman, F. R.; Elreyes, A.; Iverson, G. K. (2003). "Some principles of second language phonology". Second Language Research 19 (3): 169–208. doi:10.1191/0267658303sr2190a. .
- Cook, Vivian (2008). Second Language Learning and Language Teaching. London: Arnold. pp. 76–77. ISBN 978-0-340-95876-6..
- The term language transfer is not without controversy, however. Sharwood Smith and Kellerman preferred the term crosslinguistic influence to language transfer. They argued that cross-linguistic influence was neutral regarding different theories of language acquisition, whereas language transfer was not. Sharwood Smith & Kellerman 1986, cited in Ellis 2008, p. 350.
- Lightbown & Spada 2006, pp. 93–96.
- Ellis 2008, p. 350.
- Ellis 2008, p. 397.
- Krashen 1981a.
- Krashen 1994.
- Elley 1991.
- Krashen 2004.
- Cook 2008, p. 215.
- Krashen 1981b, pp. 54–55.
- Swain 1991.
- Skehan 1998.
- Swain 1995.
- Long 1996.
- VanPatten & Benati 2010, p. 5.
- VanPatten & Benati 2010, p. 71.
- Ellis 2008, pp. 405–406.
- Ellis 1997, p. 35.
- Ellis 2008, pp. 408–410.
- Ellis 2008, pp. 410–415.
- Ellis 2008, pp. 415–417.
- Ellis 2008, pp. 431–433.
- Ellis 2008, pp. 443–445.
- Ellis 2008, pp. 445–452.
- Ellis 2008, pp. 445–482.
- Ellis 2008, pp. 488–492.
- Ellis 2008, p. 511.
- Ellis 1997, p. 37.
- Ellis 2008, pp. 280–281.
- Ellis 2008, p. 281.
- Siegel 2003, p. 178.
- Ellis 2008, p. 288.
- Ellis 2008, p. 323.
- Ellis 2008, pp. 326–327.
- Ellis 2008, p. 330.
- Ellis 2008, p. 332.
- Watson-Gegeo & Nielsen 2003, p. 157.
- Ellis 2008, p. 334.
- Ellis 2008, p. 336.
- VanPatten & Benati 2010, pp. 151–152.
- Ellis 2008, pp. 517–518.
- Ellis 2008, p. 557.
- VanPatten & Benati 2010, p. 161.
- VanPatten & Benati 2010, pp. 162–163.
- The critical period hypothesis was formulated for first-language acquisition by Penfield & Roberts (1959) and popularized by Lenneberg (1967).
- Canale & Swain 1980.
- Erton, I. (2010). Relations between personality traits, language learning styles and success in foreign language achievement. Hacettepe University Journal of Education, 38, 155–126.
- Lightbown 1990.
- Doughty & Williams 1998.
- Ellis 2002.
- Lightbown & Spada 1990.
- Lyster & Ranta 1997.
- Lyster & Mori 2006.
- Allwright & Hanks 2009.
- Tarone & Swierzbin 2009.
- Allwright, Dick; Hanks, Judith (2009). The Developing Language Learning: An Introduction to Exploratory Practice. Basingstoke: Palgrave MacMillan. ISBN 978-1-4039-8531-6.
- Anderson, J. R. (1992). "Automaticity and the ACT* theory". American Journal of Psychology 105 (2): 165–180. doi:10.2307/1423026. JSTOR 1423026. PMID 1621879.
- Bailey, N.; Madden, C.; Krashen, S. D. (1974). "Is there a "natural sequence" in adult second language learning?". Language Learning 24 (2): 235. doi:10.1111/j.1467-1770.1974.tb00505.x.
- Bates, E.; MacWhinney, B. (1981). "Second-Language Acquisition from a Functionalist Perspective: Pragmatic, Semantic, and Perceptual Strategies". Annals of the New York Academy of Sciences 379: 190. Bibcode:1981NYASA.379..190B. doi:10.1111/j.1749-6632.1981.tb42009.x.
- Brown, Roger (1973). A First Language. Cambridge: Harvard University Press. ISBN 978-0-674-30325-6.
- Canale, M.; Swain, M. (1980). "Theoretical bases of communicative approaches to second language teaching and testing". Applied Linguistics 1 (1): 1–47. doi:10.1093/applin/1.1.1.
- Chang, Charles B. (2012). "Rapid and multifaceted effects of second-language learning on first-language speech production". Journal of Phonetics 40 (2): 249–268. doi:10.1016/j.wocn.2011.10.007.
- Cook, Vivian (2008). Second Language Learning and Language Teaching. London: Arnold. ISBN 978-0-340-95876-6.
- DeKeyser, Robert (1998). "Beyond focus on form: Cognitive perspectives on learning and practicing second language grammar". In Doughty, Catherine; Williams, Jessica. Focus on Form in Classroom Second Language Acquisition. New York: Cambridge University Press. pp. 42–63. ISBN 978-0-521-62390-2.
- Doughty, Catherine; Williams, Jessica, eds. (1998). Focus on Form in Classroom Second Language Acquisition. Cambridge: Cambridge University Press. ISBN 978-0-521-62390-2.
- Dulay, H. C.; Burt, M. K. (1973). "Should we teach children syntax?". Language Learning 23 (2): 245. doi:10.1111/j.1467-1770.1973.tb00659.x.
- Dulay, Heidi; Burt, Marina (1974a). "Natural sequences in child second language acquisition". Language Learning 24: 37–53. doi:10.1111/j.1467-1770.1974.tb00234.x.
- Dulay, Heidi; Burt, Marina (1974b). "You can't learn without goofing". In Richards, Jack. Error Analysis. New York: Longman. pp. 95–123. ISBN 978-0-582-55044-5.
- Dulay, Heidi; Burt, Marina (1975). "Creative construction in second language learning and teaching". In Dulay, Heidi; Burt, Marina. On TESOL '75: New Directions in Second Language Learning, Teaching, and Bilingual Education: Selected Papers from the Ninth Annual TESOL Convention, Los Angeles, California, March 4–9, 1975. Washington, DC: Teachers of English to Speakers of Other Languages. pp. 21–32. OCLC 1980255.
- Elley, W. B. (1991). "Acquiring Literacy in a Second Language: the Effect of Book-Based Programs". Language Learning 41 (3): 375–411. doi:10.1111/j.1467-1770.1991.tb00611.x.
- Ellis, N. C. (1998). "Emergentism, Connectionism and Language Learning". Language Learning 48 (4): 631–664. doi:10.1111/0023-8333.00063. Retrieved 2011-03-01.
- Ellis, Rod (1993). "Second language acquisition and the structural syllabus". TESOL Quarterly 27 (1): 91–113. doi:10.2307/3586953. JSTOR 3586953.
- Ellis, Rod (1994). The Study of Second Language Acquisition. Oxford Oxfordshire: Oxford University Press. ISBN 0-19-437189-1.
- Ellis, Rod (1997). Second Language Acquisition. Oxford Introductions to Language Study. Oxford, New York: Oxford University Press. ISBN 978-0-19-437212-1.
- Ellis, Rod (2002). "Does form-focused instruction affect the acquisition of implicit knowledge?". Studies in Second Language Acquisition 24 (2): 223–236. doi:10.1017/s0272263102002073.
- Ellis, Rod; Barkhuizen, Patrick (2005). Analysing Learner Language. Oxford: Oxford University Press. ISBN 978-0-19-431634-7.
- Ellis, Rod (2008). The Study of Second Language Acquisition. Oxford, UK: Oxford University Press. ISBN 978-0-19-442257-4.
- Flege, James Emil (1987). "The production of "new" and "similar" phones in a foreign language: evidence for the effect of equivalence classification". Journal of Phonetics 15: 47–65. Retrieved 2011-02-09.
- Harley, B. (1989). "Functional Grammar in French Immersion: A Classroom Experiment". Applied Linguistics 10 (3): 331–360. doi:10.1093/applin/10.3.331.
- Haynes, Judie (2007). Getting Started With English Language Learners: How Educators Can Meet the Challenge. Alexandria, VA: Association for Supervision and Curriculum Development. ISBN 978-1-4166-0519-5.
- Krashen, Stephen (1977). "Some issues relating to the monitor model". In Brown, H; Yorio, Carlos; Crymes, Ruth. Teaching and learning English as a Second Language: Trends in Research and Practice: On TESOL '77: Selected Papers from the Eleventh Annual Convention of Teachers of English to Speakers of Other Languages, Miami, Florida, April 26 – May 1, 1977. Washington, DC: Teachers of English to Speakers of Other Languages. pp. 144–158. OCLC 4037133.
- Krashen, Stephen (1981a). Second Language Acquisition and Second Language Learning. New York: Pergamon Press. ISBN 0-08-025338-5. Retrieved 2011-02-28.
- Krashen, Stephen (1981b). "The "fundamental pedagogical principle" in second language teaching". Studia Linguistica 35: 50–70. doi:10.1111/j.1467-9582.1981.tb00701.x. Retrieved 2011-03-24.
- Krashen, Stephen (1982). Principles and Practice in Second Language Acquisition. Pergamon Press. ISBN 0-08-028628-3. Retrieved 2010-11-25.
- Krashen, Stephen (1994). "The input hypothesis and its rivals". In Ellis, Nick. Implicit and Explicit Learning of Languages. London: Academic Press. pp. 45–77. ISBN 978-0-12-237475-3.
- Krashen, Stephen (2004). The Power of Reading, Second Edition. Littleton: Libraries Unlimited. ISBN 978-1-59158-169-7.
- Lenneberg, Eric (1967). Biological Foundations of Language. New York: Wiley. ISBN 0-89874-700-7.
- Lightbown, Patsy (1990). "Chapter 6: Process-product research on second language learning in classrooms". In Harley, Birgit. The Development of Second Language Proficiency. Cambridge, New York: Cambridge University Press. pp. 82–92. ISBN 978-0-521-38410-0.
- Lightbown, Patsy; Spada, Nina (1990). "Focus-on-Form and Corrective Feedback in Communicative Language Teaching: Effects on Second Language Learning". Studies in Second Language Acquisition 12 (4): 429–48. doi:10.1017/S0272263100009517.
- Lightbown, Patsy M.; Spada, Nina (2006). How Languages Are Learned (3rd ed.). Oxford, New York: Oxford University Press. ISBN 978-0-19-442224-6.
- Long, M. (1996). "The role of the linguistic environment in second language acquisition". In Ritchie, William; Bhatia, Tej. Handbook of Second Language Acquisition. San Diego: Academic Press. pp. 413–468. ISBN 978-0-12-589042-7.
- Lyster, R.; Ranta, L. (1997). "Corrective feedback and learner uptake: Negotiation of form in communicative classrooms". Studies in Second Language Acquisition 19: 37–66. doi:10.1017/s0272263197001034.
- Lyster, R.; Mori, H. (2006). "Interactional feedback and instructional counterbalance". Studies in Second Language Acquisition 28: 269–300. doi:10.1017/s0272263106060128.
- MacWhinney, Brian (1987). "Applying the Competition Model to bilingualism". Applied Psycholinguistics 8 (4): 315–327. doi:10.1017/S0142716400000357. Retrieved 2011-03-02.
- MacWhinney, B. (2005). "Extending the Competition Model". International Journal of Bilingualism 9: 69–05. doi:10.1177/13670069050090010501.
- Paradis, M. (1994). "Neurolinguistic aspects of implicit and explicit memory: Implications for bilingualism and SLA". In Ellis, Nick. Implicit and Explicit Learning of Languages. London: Academic Press. pp. 393–420. ISBN 978-0-12-237475-3.
- Penfield, Wilder; Roberts, Lamar (1959). Speech and Brain Mechanisms. Princeton: Princeton University Press. ISBN 0-691-08039-9.
- Prabhu, N. (1987). Second Language Pedagogy. Oxford: Oxford University Press. ISBN 978-0-19-437084-4.
- Rounds, P. L.; Kanagy, R. (1998). "Acquiring linguistic cues to identify AGENT: Evidence from children learning Japanese as a second language". Studies in Second Language Acquisition 20 (4): 509–542. doi:10.1017/s0272263198004033.
- Schmidt, R. (2001). "Attention". In Robinson, Peter. Cognition and Second Language Instruction. Cambridge: Cambridge University Press. pp. 1–32. ISBN 978-0-521-80288-8.
- Siegel, Jeff (2003). "Social Context". In Doughty, Catherine; Long, Michael. The handbook of second language acquisition. Malden, MA: Blackwell. ISBN 978-0-631-21754-1.
- Skehan, Peter (1998). A Cognitive Approach to Language Learning. Oxford: Oxford University Press. ISBN 978-0-19-437217-6.
- Swain, Merrill (1991). "French immersion and its offshoots: Getting two for one". In Freed, Barbara. Foreign language acquisition research and the classroom. Lexington, MA: Heath. pp. 91–103. ISBN 978-0-669-24263-8.
- Swain, Merrill (1995). "Three functions of output in second language learning". In Cook, Guy. Principle & Practice in Applied Linguistics: Studies in Honour of H.G. Widdowson. Oxford: Oxford University Press. pp. 125–144. ISBN 978-0-19-442147-8.
- Tarone, Elaine; Bigelow, Martha; Hansen, Kit (2009). Literacy and Second Language Oracy. Oxford: Oxford University Press. ISBN 978-0-19-442300-7.
- Tarone, Elaine; Swierzbin, Bonnie (2009). Exploring Learner Language. Oxford: Oxford University Press. ISBN 978-0-19-442291-8.
- VanPatten, Bill; Benati, Alessandro G. (2010). Key Terms in Second Language Acquisition. London: Continuum. ISBN 978-0-8264-9914-1.
- Watson-Gegeo, Karen Ann; Nielsen, Sarah (2003). "Language Socialization in SLA". In Doughty, Catherine; Long, Michael. The handbook of second language acquisition. Malden, MA: Blackwell. ISBN 978-0-631-21754-1.
- Yuan, F.; Ellis, R. (2003). "The Effects of Pre-Task Planning and On-Line Planning on Fluency, Complexity and Accuracy in L2 Monologic Oral Production". Applied Linguistics 24: 1. doi:10.1093/applin/24.1.1.
- Ellis, Rod. (2007). Educational Settings and Second Language Learning. Volume 9 Asian EFL Journal. 
- Ellis, Rod. (2005). Principles of Instructed Language Learning. Volume 7 Asian EFL Journal.
- Lightbown, P. and Spada, N. (2006). How Languages are Learned. Oxford: Oxford University Press. 2nd edition. [ISBN 0-19-442224-0]
- Lin, G. H. C. (2008). "Lin, G. H. C. (2008). Pedagogies proving Krashen’s theory of affective filter , Hwa Kang Journal of English Language & Literature, Vol, 14, pp.113–131 ERIC Collection as ED503681 
- Ellis, Rod (1991). "The Interaction Hypothesis A critical evaluation". p. 37 – on Michael H. Long's Interaction Hypothesis
- Mangubhai, F. (2006). "What do we know about learning and teaching second languages: Implications for teaching " Asian EFL Journal Vol 8. 2006 
- McKay, Sharon; Schaetzel, Kirsten, Facilitating Adult Learner Interactions to Build Listening and Speaking Skills, CAELA Network Briefs, CAELA and Center for Applied Linguistics
- Mitchell, R. and Myles, F. (2004). Second Language Learning Theories (2nd ed). London: Hodder Arnold.
- Norris, J. M., & Ortega, L. (2006). (Eds.). Synthesizing research on language learning and teaching. John Benjamins: Amsterdam/Philadelphia.
- Ortega, L. (2009). Understanding Second Language Acquisition. London: Hodder Arnold.
- Ortega, L. (2010). Second language acquisition. Critical concepts in linguistics. London: Routledge. [ISBN 978-0-415-45020-1]
- Oxford, R,. & Lee, K. (2008). Understanding EFL Learners’ Strategy Use and Strategy Awareness.
- Robertson, P. & Nunn, R. (2007). The Study of Second Language Acquisition in the Asian Context 
- Tarone, E. & Swierzbin, B. (2009). Exploring Learner Language. Oxford: Oxford University Press.
- Thomas, M. (2009). Handbook of Research on Web 2.0 and Second Language Learning. IGI Global Sippnet.
- White, L. (2003). Second Language Acquisition and Universal Grammar. Cambridge: Cambridge University Press.
|Wikibooks has a book on the topic of: Language Learning Difficulty for English Speakers|
- Center for Applied Linguistics homepage
- Didactics of English. A lecture series in SLA by Timothy Mason, run from 1993 to 2002 at the Université of Versailles St. Quentin.
- Second Language Acquisition Topics by Vivian Cook: information on SLA, applied linguistics and language teaching research, including a large bibliography.