Error analysis

Error analysis
Error analysis in SLA was established in the 1960s by Stephen Pit Corder and colleagues (Corder, 1967). Error analysis was an alternative to contrastive analysis, an approach influenced by behaviorism through which applied linguists sought to use the formal distinctions between the
Error analysis showed that contrastive analysis was unable to predict a great majority of errors, although its more valuable aspects have been incorporated into the study of language transfer. A key finding of error analysis has been that many learner errors are produced by learners making faulty inferences about the rules of the new language.
Error analysts distinguish between errors, which are systematic, and mistakes, which are not. They often seek to develop a typology of errors. Error can be classified according to basic type: omissive, additive, substitutive or related to word order. They can be classified by how apparent they are: overt errors such as "I angry" are obvious even out of context, whereas covert errors are evident only in context. Closely related to this is the classification according to domain, the breadth of context which the analyst must examine, and extent, the breadth of the utterance which must be changed in order to fix the error. Errors may also be classified according to the level of language: phonological errors, vocabulary or lexical errors, syntactic errors, and so on. They may be assessed according to the degree to which they interfere with communication: global errors make an utterance difficult to understand, while local errors do not. In the above example, "I angry" would be a local error, since the meaning is apparent.
From the beginning, error analysis was beset with methodological problems. In particular, the above typologies are problematic: from linguistic data alone, it is often impossible to reliably determine what kind of error a learner is making. Also, error analysis can deal effectively only with learner production (speaking and writing) and not with learner reception (listening and reading). Furthermore, it cannot account for learner use of communicative strategies such as avoidance, in which learners simply do not use a form with which they are uncomfortable. For these reasons, although error analysis is still used to investigate specific questions in SLA, the quest for an overarching theory of learner errors has largely been abandoned. In the mid-1970s, Corder and others moved on to a more wide-ranging approach to learner language, known as interlanguage.
Error analysis is closely related to the study of error treatment in language teaching. Today, the study of errors is particularly relevant for focus on form teaching methodology.

Interlanguage
Interlanguage is a term coined by Selinker (1972). Interlanguage scholarship seeks to understand learner language on its own terms, as a natural language with its own systematic rules. Interlanguage scholars reject, at least for heuristic purposes, the view of learner language as merely an imperfect version of the target language. Interlanguage work is a vibrant microcosm of linguistics. It is possible to apply an interlanguage perspective to learners' underlying knowledge of the target language sound system (interlanguage phonology), grammar (morphology and syntax), vocabulary (lexicon), and language-use norms found among learners (interlanguage pragmatics).
By describing the ways in which learner language conforms to universal linguistic norms, interlanguage research has contributed greatly to our understanding of linguistic universals in SLA. See below, under "linguistic universals".
Developmental patterns
Ellis (1994)[vague] distinguished between "order" to refer to the pattern in which different language features are acquired and "sequence" to denote the pattern by which a specific language feature is acquired.
Order of acquisition
Researchers have found a very consistent order in the acquisition of first language structures by children, and this has drawn a great deal of interest from SLA scholars. Considerable effort has been devoted to testing the "identity hypothesis", which asserts that first-language and second-language acquisition conform to the same patterns. This has not been confirmed, perhaps because second-language learners' cognitive and affective states are so much more advanced, and perhaps because it is not true. Orders of acquisition in SLA often resemble those found in first language acquisition, and may have common neurological causes, but there is no convincing evidence for this. It is not safe to say that the order of L1 acquisition has any easy implications for SLA.
Some research suggests that most learners begin their acquisition process with a "silent period", in which they speak very little if at all. It is said that for some, this is a period of language shock, in which the learner actively rejects the incomprehensible input of the new language. However, research has shown that many "silent" learners are engaging in private speech (sometimes called "self-talk"). While appearing silent, they are rehearsing important survival phrases and lexical chunks. These memorized phrases are then employed in the subsequent period of formulaic speech. Whether by choice or compulsion, other learners have no silent period and pass directly to formulaic speech. This speech, in which a handful of routines is used to accomplish basic purposes, often shows few departures from L2 morphosyntax. It eventually gives way to a more experimental phase of acquisition, in which the semantics and grammar of the target language are simplified and the learners begin to construct a true interlanguage(Seidner, (1982), pp. 9–10).
The nature of the transition between formulaic and simplified speech is disputed. Some, including Krashen, have argued that there is no cognitive relationship between the two, and that the transition is abrupt. Thinkers influenced by recent theories of the lexicon have preferred to view even native speaker speech as heavily formulaic, and interpret the transition as a process of gradually developing a broader repertoire of chunks and a deeper understanding of the rules which govern them. Some studies have supported both views, and it is likely that the relationship depends in great part on the learning styles of individual learners.
A flurry of studies took place in the 1970s, examining whether a consistent order of morpheme acquisition could be shown. Most of these studies did show fairly consistent orders of acquisition for selected morphemes. For example, among learners of English the cluster of features including the suffix "-ing", the plural, and the copula were found to consistently precede others such as the article, auxiliary, and third person singular. However, these studies were widely criticized as not paying sufficient attention to overuse of the features (idiosyncratic uses outside what are obligatory contexts in the L2), and sporadic but inconsistent use of the features. More recent scholarship prefers to view the acquisition of each linguistic feature as a gradual and complex process. For that reason most scholarship since the 1980s has focused on the sequence, rather than the order, of feature acquisition.
Sequence of acquisition
A number of studies have looked into the sequence of acquisition of pronouns by learners of various Indo-European languages. These are reviewed by Ellis (1994), pp. 96–99. They show that learners begin by omitting pronouns or using them indiscriminately: for example, using "I" to refer to all agents. Learners then acquire a single pronoun feature, often person, followed by number and eventually by gender. Little evidence of interference from the learner's first language has been found; it appears that learners use pronouns based entirely on their inferences about target language structure.
Studies on the acquisition of word order in German have shown that most learners begin with a word order based on their native language. This indicates that certain aspects of interlanguage syntax are influenced by the learners' first language, although others are not.
Research on the sequence of acquisition of words is exhaustively reviewed by Nation (2001). Kasper and Rose (2002) have thoroughly researched the sequence of acquisition of pragmatic features. In both fields, consistent patterns have emerged and have been the object of considerable theorizing.
Variability
Though the interlanguage perspective views learner language as a language in its own right, this language systematically varies much more than native-speaker language. A learner may produce a target-like variant (e.g. 'I don't') in one context and a non-target like variant (e.g. 'me no') in another. Scholars from different traditions have taken opposing views on the importance of this phenomenon. Those who bring a Chomskyan perspective to SLA typically regard variability as nothing more than "performance errors", and not worthy of systematic inquiry. On the other hand, those who approach it from a sociolinguistic or psycholinguistic orientation view variability as an inherent feature of the learner's interlanguage, where the learner's preference for one linguistic variant over another depends on accompanying a) social (contextual) variables such as the status or role of the interlocutor (see Selinker & Douglas, 1985), or b) linguistic variables such as the phonological environment or neighoring features marked for formality or informality. Naturally, most research on variability has been done by those who presume it to be meaningful (Fasold & Preston, 2007; Tarone, 2009; Tarone & Liu, 1995).
Research on variability in learner language distinguishes between "free variation", which has not been shown to be systematically related to accompanying linguistic or social features, and "systematic variation", which has. Of course, the line between the two is subject to debate.
Free variation in the use of a language feature is usually taken as a sign that it has not been fully acquired. The learner is still trying to figure out what rules govern the use of alternate forms. This type of variability seems to be most common among beginning learners, and may be entirely absent among the more advanced.
Systematic variation is brought about by changes in the linguistic, psychological, social context. Linguistic factors are usually extremely local. For instance, the pronunciation of a difficult phoneme may depend on whether it is to be found at the beginning or end of a syllable.
Social factors may include a change in register or the familiarity of interlocutors. In accordance with Communication Accommodation Theory, learners may adapt their speech to either converge with, or diverge from, their interlocutor's usage. For example, they may deliberately choose to address a non-target form like "me no" to an English teacher in order to assert identity with a non-mainstream ethnic group (Rampton 1995).
The most important psychological factor is usually taken to be attention to form, which is related to planning time. The more time that learners have to plan, the more target-like their production may be. Thus, literate learners may produce much more target-like forms in a writing task for which they have 30 minutes to plan, than in conversation where they must produce language with almost no planning at all. The impact of alphabetic literacy level on an L2 learner's ability to pay attention to form is as yet unclear (see Tarone, Bigelow & Hansen, 2009).
Affective factors also play an important role in systematic variation. For example, learners in a stressful situation (such as a formal exam) may produce fewer target-like forms than they would in a comfortable setting. This clearly interacts with social factors, and attitudes toward the interlocutor and topic also play important roles.
Learner-external factors
The study of learner-external factors in SLA is primarily concerned with the question: How do learners get information about the target language? Study has focused on the effects of different kinds of input, and on the impact of the social context.
Social effects
The process of language learning can be very stressful, and the impact of positive or negative attitudes from the surrounding society can be critical. One aspect that has received particular attention is the relationship of gender roles to language achievement. Studies across numerous cultures have shown that women, on the whole, enjoy an advantage over men. Some have proposed that this is linked to gender roles. Doman (2006) notes in a journal devoted to issues of Cultural affects on SLA, "Questions abound about what defines SLA, how far its borders extend, and what the attributions and contributions of its research are. Thus, there is a great amount of heterogeneity in the entire conceptualization of SLA. Some researchers tend to ignore certain aspects of the field, while others scrutinize those same aspects piece by piece."
Community attitudes toward the language being learned can also have a profound impact on SLA. Where the community has a broadly negative view of the target language and its speakers, or a negative view of its relation to them, learning is typically much more difficult. This finding has been confirmed by research in numerous contexts. A widely-cited example is the difficulty faced by Navajo children in learning English as a second language.
Other common social factors include the attitude of parents toward language study, and the nature of group dynamics in the language classroom. Additionally, early attitudes may strengthen motivation and facility with language in general, particularly with early exposure to the language.
Input and intake
Learners' most direct source of information about the target language is the target language itself. When they come into direct contact with the target language, this is referred to as "input." When learners process that language in a way that can contribute to learning, this is referred to as "intake."
Generally speaking, the amount of input learners take in is one of the most important factors affecting their learning. However, it must be at a level that is comprehensible to them. In his Monitor Theory, Krashen advanced the concept that language input should be at the "i+1" level, just beyond what the learner can fully understand; this input is comprehensible, but contains structures that are not yet fully understood. This has been criticized on the basis that there is no clear definition of i+1, and that factors other than structural difficulty (such as interest or presentation) can affect whether input is actually turned into intake. The concept has been quantified, however, in vocabulary acquisition research; Nation (2001) reviews various studies which indicate that about 98% of the words in running text should be previously known in order for extensive reading to be effective.
A great deal of research has taken place on input enhancement, the ways in which input may be altered so as to direct learners' attention to linguistically important areas. Input enhancement might include bold-faced vocabulary words or marginal glosses in a reading text. Research here is closely linked to research on pedagogical effects, and comparably diverse.
Interaction
Long's interaction hypothesis proposes that language acquisition is strongly facilitated by the use of the target language in interaction. In particular, the negotiation of meaning has been shown to contribute greatly to the acquisition of vocabulary (Long, 1990). In a review of the substantial literature on this topic, Nation (2000) relates the value of negotiation to the generative use of words: the use of words in new contexts which stimulate a deeper understanding of their meaning.
In the 1980s, Canadian SLA researcher Merrill Swain advanced the output hypothesis, that meaningful output is as necessary to language learning as meaningful input. However, most studies have shown little if any correlation between learning and quantity of output. Today, most scholars[citation needed] contend that small amounts of meaningful output are important to language learning, but primarily because the experience of producing language leads to more effective processing of input.
Pedagogical effects
Efforts have been made to systematically measure or evaluate the effectiveness of language teaching practices in promoting second language acquisition. Such studies have been undertaken for every level of language, from phonetics to pragmatics, and for almost every current teaching methodology. It is therefore impossible to summarize their findings here. However, some more general issues have been addressed.
Research has indicated that many traditional language-teaching techniques are extremely inefficient. (P Lightbown, 1990) One issue is the effectiveness of explicit teaching: can language teaching have a constructive effect beyond providing learners with enhanced input? Research on this at different levels of language has produced quite different results. Traditional areas of explicit teaching, such as phonology, grammar and vocabulary, have had decidedly mixed results. 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 L2, the learner must be given opportunities to use the L2 for communicative purposes, learning (as for example, through a teacher's corrective feedback) to attend to both meaning and formal accuracy (Doughty & Williams 1998; Ellis 2002).
There is considerable promising research in the classroom on the impact of corrective feedback on L2 learners' use and acquisition of target language forms. The effectiveness of corrective feedback 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 (Lightbown & Spada, 1990; Lyster & Ranta, 1997; Lyster & Mori, 2006). However, it appears that a learner's ability to focus on corrective feedback on grammatical features that do not affect meaning is considerably altered when the learner has low alphabetic literacy (Tarone, Bigelow & Hansen 2009).
There is considerable interest in supplementing published research with approaches that engage language teachers in action research on learner language in their own classrooms (Allwright & Hanks, 2009). As teachers become aware of the features of learner language produced by their students, they can refine their pedagogical intervention to maximize interlanguage development (Tarone & Swierzbin 2009).
Learner-internal factors
The study of learner-internal factors in SLA is primarily concerned with the question: How do learners gain competence in the target language? In other words, given effective input and instruction, with what internal resources do learners process this input to produce a rule-governed interlanguage?
Critical period research to date
How children acquire native language (L1) and the relevance of this to foreign language (L2) learning has long been debated. Although evidence for L2 learning ability declining with age is controversial, a common notion is that children learn L2s easily and older learners rarely achieve fluency. This assumption stems from ‘critical period’ (CP) ideas. A CP was popularised by Eric Lenneberg in 1967 for L1 acquisition, but considerable interest now surrounds age effects on second language acquisition (SLA). SLA theories explain learning processes and suggest causal factors for a possible CP for SLA, mainly attempting to explain apparent differences in language aptitudes of children and adults by distinct learning routes, and clarifying them through psychological mechanisms. Research explores these ideas and hypotheses, but results are varied: some demonstrate pre-pubescent children acquire language easily, and some that older learners have the advantage, and yet others focus on existence of a CP for SLA. Recent studies (e.g. Mayberry and Lock, 2003) have recognised that certain aspects of SLA may be affected by age, though others remain intact. The objective of this study is to investigate whether capacity for vocabulary acquisition decreases with age.
A review of SLA theories and their explanations for age-related differences is necessary before considering empirical studies. The most reductionist theories are those of Penfield and Roberts (1959) and Lenneberg (1967), which stem from L1 and brain damage studies; children who suffer impairment before puberty typically recover and (re-)develop normal language, whereas adults rarely recover fully, and often do not regain verbal abilities beyond the point reached five months after impairment. Both theories agree that children have a neurological advantage in learning languages, and that puberty correlates with a turning point in ability. They assert that language acquisition occurs primarily, possibly exclusively, during childhood as the brain loses plasticity after a certain age. It then becomes rigid and fixed, and loses the ability for adaptation and reorganisation, rendering language (re-)learning difficult.
Cases of deaf and feral children provide evidence for a biologically determined CP for L1. Feral children are those not exposed to language in infancy/childhood due to being brought up in the wild, in isolation and/or confinement. A classic example is 'Genie', who was deprived of social interaction from birth until discovered aged thirteen (post-pubescent).
Such studies are however problematic; isolation can result in general retardation and emotional disturbances, which may confound conclusions drawn about language abilities. Studies of deaf children learning American Sign Language (ASL) have fewer methodological weaknesses. Newport and Supalla (1987) studied ASL acquisition in deaf children differing in age of exposure; few were exposed to ASL from birth, most of them first learned it at school.
Results showed a linear decline in performance with increasing age of exposure; those exposed to ASL from birth performed best, and ‘late learners’ worst, on all production and comprehension tests. Their study thus provides direct evidence for language learning ability decreasing with age, but it does not add to Lennerberg’s CP hypothesis as even the oldest children, the ‘late learners’, were exposed to ASL by age four, and had therefore not reached puberty, the proposed end of the CP.
Other work has challenged the biological approach; Krashen (1975) reanalysed clinical data used as evidence and concluded cerebral specialisation occurs much earlier than Lenneberg calculated. Therefore, if a CP exists, it does not coincide with lateralisation.
Although it does not describe an optimal age for SLA, the theory implies that younger children can learn languages more easily than older learners, as adults must reactivate principles developed during L1 learning and forge an SLA path: children can learn several languages simultaneously as long as the principles are still active and they are exposed to sufficient language samples (Pinker, 1995).
There are, however, problems with the extrapolation of the UG theory to SLA: L2 learners go through several phases of types of utterance that are not similar to their L1 or the L2 they hear. Other factors include the cognitive maturity of most L2 learners, that they have different motivation for learning the language, and already speak one language fluently.

Other directions of research
Virtually all research findings on SLA to date build on data from literate learners. Tarone, Bigelow and Hansen (2009) find significantly different results when replicating standard SLA studies with low literate L2 learners. Specifically, learners with lower alphabetic literacy levels are significantly less likely to notice corrective feedback on form or to perform elicited imitation tasks accurately. These findings are consistent with research in cognitive psychology showing significant differences in phonological awareness between literate and illiterate adults (Reis and Castro-Caldas 1997; Castro-Caldas et al. 1998). An important direction for SLA research must therefore involve the exploration of the impact of alphabetic literacy on cognitive processing in second language acquisition.
Empirical research has attempted to account for variables detailed by SLA theories and provide an insight into L2 learning processes, which can be applied in educational environments. Recent SLA investigations have followed two main directions: one focuses on pairings of L1 and L2 that render L2 acquisition particularly difficult, and the other investigates certain aspects of language that may be maturationally constrained. Flege, Mackay and Piske (2002) looked at bilingual dominance to evaluate two explanations of L2 performance differences between bilinguals and monolingual-L2 speakers, i.e. a maturationally defined CP or interlingual interference.
Flege, Mackay and Piske investigated whether the age at which participants learned English affected dominance in Italian-English bilinguals, and found the early bilinguals were English (L2) dominant and the late bilinguals Italian (L1) dominant. Further analysis showed that dominant Italian bilinguals had detectable foreign accents when speaking English, but early bilinguals (English dominant) had no accents in either language. This suggests that, though interlingual interference effects are not inevitable, their emergence, and bilingual dominance, may be related to a CP.
Sebastián-Gallés, Echeverría and Bosch (2005) also studied bilinguals and highlight the importance of early language exposure. They looked at vocabulary processing and representation in Spanish-Catalan bilinguals exposed to both languages simultaneously from birth in comparison to those who had learned L2 later and were either Spanish- or Catalan-dominant. Findings showed ‘from birth bilinguals’ had significantly more difficulty distinguishing Catalan words from non-words differing in specific vowels than Catalan-dominants did (measured by reaction time).
These difficulties are attributed to a phase around age eight months where bilingual infants are insensitive to vowel contrasts, despite the language they hear most. This affects how words are later represented in their lexicons, highlighting this as a decisive period in language acquisition and showing that initial language exposure shapes linguistic processing for life. Sebastián-Gallés et al. (2005) also indicate the significance of phonology for L2 learning; they believe learning an L2 once the L1 phonology is already internalised can reduce individuals’ abilities to distinguish new sounds that appear in the L2.
Most studies into age effects on specific aspects of SLA have focused on grammar, with the common conclusion that it is highly constrained by age, more so than semantic functioning. B. Harley (1986) compared attainment of French learners in early and late immersion programs. She reports that after 1000 exposure hours, late learners had better control of French verb systems and syntax. However, comparing early immersion students (average age 6.917 years) with age-matched native speakers identified common problem areas, including third person plurals and polite ‘vous’ forms. This suggests grammar (in L1 or L2) is generally acquired later, possibly because it requires abstract cognition and reasoning (B. Harley, 1986).
B. Harley also measured eventual attainment and found the two age groups made similar mistakes in syntax and lexical selection, often confusing French with the L1. The general conclusion from these investigations is that different aged learners acquire the various aspects of language with varying difficulty. Some variation in grammatical performance is attributed to maturation (discussed in B. Harley, 1986), however, all participants began immersion programs before puberty and so were too young for a strong critical period hypothesis to be directly tested.
Mayberry and Lock (2003) questioned whether age restrains both L1 and L2 acquisition. They examined grammatical abilities of deaf and hearing adults who had their initial linguistic exposure either in early childhood or later. They found that, on L2 grammatical tasks, those who had acquired the verbal or signed L1 early in life showed near-native performance and those who had no early L1 experience (i.e. born deaf and parents did not know sign-language) performed weakly. Mayberry and Lock concluded early L1 exposure is vital for forming life-long learning abilities, regardless of the nature of the exposure (verbal or signed language). This corresponds to Noam Chomsky’s UG theory, which states that while language acquisition principles are still active, it is easy to learn a language, and the principles developed through L1 acquisition are vital for learning an L2.
Scherag, Demuth, Rösler, Neville and Röder (2004) also suggest learning some syntactic processing functions and lexical access may be limited by maturation, whereas semantic functions are relatively unaffected by age. They studied the effect of late SLA on speech comprehension by German immigrants to the U.S.A. and American immigrants to Germany. They found that native-English speakers who learned German as adults were disadvantaged on certain grammatical tasks but performed at near-native levels on lexical tasks. These findings are consistent with work by Hahne (2001, cited in Scherag et al., 2004).
One study that specifically mentions semantic functions acquisition is that of Weber-Fox and Neville (1996). Their results showed that Chinese-English bilinguals who had been exposed to English after puberty, learned vocabulary to a higher competence level than syntactic aspects of language. They do, however, report that the judgment accuracies in detecting semantic anomalies were altered in subjects who were exposed to English after sixteen years of age, but were affected to a lesser degree than were grammatical aspects of language. It has been speculated (Neville and Bavelier, 2001, and Scherag et al., 2004) that semantic aspects of language are founded on associative learning mechanisms, which allow life-long learning, whereas syntactical aspects are based on computational mechanisms, which can only be constructed during certain age periods. Consequently, it is reasoned, semantic functions are easier to access during comprehension of an L2 and therefore dominate the process: if these are ambiguous, understanding of syntactic information is not facilitated. These suppositions would help explain the results of Scherag et al.’s (2004) study.
Some researchers have focused exclusively on practical applications of SLA research. Asher (1972) insists teenagers and adults rarely successfully learn an L2, and attributes this to teaching strategies. He presents an L2 teaching strategy based on infants’ L1 acquisition, which promotes listening as central in language learning: listening precedes, and generates a ‘readiness’ for, speaking, assumptions supported by Carroll (1960). Asher shows that in L2 acquisition, in this case German, listening fluency is achieved in around half the usual time if the teaching is based on L1 acquisition, and that learners taught in this way still develop reading and writing proficiency comparable with those whose training emphasises literacy skills.
Similarly Horwitz (1986) summarises findings of SLA research, and applies to L2 teaching some principles of L2 acquisition honed from a vast body of relevant literature. Like Asher, Horwitz highlights the importance of naturalistic experience in L2, promoting listening and reading practice and stressing involvement in life-like conversations. She explicitly suggests teaching practices based on these principles; ‘[m]uch class time should be devoted to the development of listening and reading abilities’, and ‘[t]eachers should assess student interests and supply appropriate…materials’ (Horwitz, 1986, p. 685-686). The ‘audio-lingual’ teaching practices used in the present study are based on principles explicated by Asher and Horwitz; listening featured heavily, closely followed by reading and speaking practice. The vocabulary items taught were deemed relevant for all learners, regardless of age, and, according to Pfeffer (1964), they are among the most commonly used nouns in everyday German language.
Cognitive approaches
Another line of theory and research uses cognitive science to seek to understand how second language (L2) learners internally process language information. In doing so, formal understandings have been challenged, as these cognitive approaches have offered alternative conceptions of SLA processes. Below is an overview of the major products of cognitive speculation and research. Specifically described are cognitive-related concepts and evidence related to how individuals (1) structure L2 knowledge, (2) use those structures to comprehend and produce in second languages, and (3) restructure language knowledge as their L2 proficiencies increase.
Structuring Second Language Knowledge
Some of the major cognitive theories of how learners organize language knowledge are based on analyses of how speakers of various languages analyze sentences for meaning. MacWhinney, Bates, and Kliegl (1984) found that speakers of English, German, and Italian showed varying patterns in identifying the subjects of transitive sentences containing more than one noun. English speakers relied heavily on word order; German speakers used morphological agreement, the animacy status of noun referents, and stress; and speakers of Italian relied on agreement and stress. MacWhinney et al. interpreted these results as supporting the Competition Model, which states that individuals use linguistic cues to get meaning from language, rather than relying on linguistic universals. According to this theory, when acquiring an L2, learners sometimes receive competing cues and must decide which cue(s) is most relevant for determining meaning.
These findings also relate to Connectionism. Connectionism attempts to model the cognitive language processing of the human brain, using computer architectures that make associations between elements of language, based on frequency of co-occurrence in the language input (Christiansen & Chater, 2001). Frequency has been found to be a factor in various linguistic domains of language learning (Ellis, 2002). Connectionism posits that learners form mental connections between items that co-occur, using exemplars found in language input. From this input, learners extract the rules of the language through cognitive processes common to other areas of cognitive skill acquisition. Since connectionism denies both innate rules and the existence of any innate language-learning module, L2 input is of greater importance than it is in processing models based on innate approaches, since, in connectionism, input is the source of both the units and the rules of language.
Other concepts have also been influential in the speculation about the processes of building internal systems of second language information. Some thinkers hold that language processing handles distinct types of knowledge. For instance, one component of the Monitor Model, propounded by Krashen (1982), posits a distinction between “acquisition” and “learning.” According to Krashen, L2 acquisition is a subconscious process of incidentally “picking up” a language, as children do when becoming proficient in their first languages. Language learning, on the other hand, is studying, consciously and intentionally, the features of a language, as is common in traditional classrooms. Krashen sees these two processes as fundamentally different, with little or no interface between them. In common with connectionism, Krashen (1982) sees input as essential to language acquisition. In his Input Hypothesis, he proposes that language acquisition takes place only when learners receive input just beyond their current level of L2 competence. He termed this level of input “i+1.” However, in contrast to emergentist and connectionist theories, he follows the innate approach by applying Chomsky (1981, 1986)’s Binding/Government theory and concept of Universal Grammar (UG) to SLA. He does so by proposing a Language Acquisition Device that uses L2 input to define the parameters of the L2, within the constraints of UG, and to increase the L2 proficiency of the learner. In addition, Krashen (1982)’s Affective Filter Hypothesis holds that the acquisition of a second language is halted if the leaner has a high degree of anxiety when receiving input. According to this concept, a part of the mind filters out L2 input and prevents uptake by the learner, if the learner feels that the process of SLA is threatening. As mentioned earlier, since input is essential in Krashen’s model, this filtering action prevents acquisition from progressing.
A distinction closely related to that made by Krashen (1982) between acquisition and learning is one between implicit and explicit linguistic knowledge. Learners gain implicit knowledge by processing target-language input without consciously giving attention to acquiring the forms and structures of the language. On the other hand, learners get explicit knowledge of a language when they process language input with the conscious intention of discovering the structural rules of the language. A distinction between the implicit learning involved in acquiring a first language (L1) and the mix of implicit and explicit learning that takes place in L2 acquisition has been one analytic route for understanding the virtually universal success of L1 acquisition versus the more limited success of L2 acquisition among adult learners (Hulstijn, 2005). Ellis (2005) has found empirical confirmation for the distinct constructs of implicit and explicit language knowledge. Some have used a declarative/procedural model to understand how language information is stored. This model is consistent with a distinction made in general cognitive science between the storage and retrieval of facts, on the one hand, and understanding of how to carry out operations, on the other. It states that declarative knowledge consists of arbitrary linguistic information, such as irregular verb forms, that are stored in the brain’s declarative memory. In contrast, knowledge about the rules of a language, such as grammatical word order is procedural knowledge and is stored in procedural memory. Ullman (2001) reviews several psycholinguistic and neurolinguistic studies that support the declarative/procedural model.
Further, Bialystok and Smith (1985) make another distinction in explaining how learners build and use L2 and interlanguage knowledge structures. They argue that the concept of interlanguage should include a distinction between two specific kinds of language processing ability. On one hand is learners’ knowledge of L2 grammatical structure and ability to analyze the target language objectively using that knowledge, which they term “representation,” and, on the other hand is the ability to use their L2 linguistic knowledge, under time constraints, to accurately comprehend input and produce output in the L2, which they call “control.” They point out that often non-native speakers of a language have higher levels of representation than their native-speaking counterparts have, yet have a lower level of control. Finally, Bialystok (1994) has framed the acquisition of language in terms of the interaction between what she calls “analysis” and “control.” Analysis is what learners do when they attempt to understand to be the rules of the target language. Through this process, they acquire these rules and can use them to gain greater control over their own production.
Using Second Language Knowledge Structures
Thinkers have produced several theories concerning how learners use their internal L2 knowledge structures to comprehend L2 input and produce L2 output. One idea is that learners acquire proficiency in an L2 in the same way that people acquire other complex cognitive skills. Automaticity is the performance of a skill without conscious control. It results from the gradated process of proceduralization. In the field of cognitive psychology, Anderson (1992) expounds a model of skill acquisition, according to which persons use procedures to apply their declarative knowledge about a subject in order to solve problems. On repeated practice, these procedures develop into production rules that the individual can use to solve the problem, without accessing long-term declarative memory. Performance speed and accuracy improve as the learner implements these production rules. DeKeyser (1997) tested the application of this model to L2 language automaticity. He found that subjects developed increasing proficiency in performing tasks related to the morphosyntax of an artificial language, Autopractan, and performed on a learning curve typical of the acquisition of non-language cognitive skills. This evidence conforms to Anderson’s general model of cognitive skill acquisition, supports the idea that declarative knowledge can be transformed into procedural knowledge, and tends to undermine the idea of Krashen (1982) that knowledge gained through language “learning” cannot be used to initiate speech production.
Monitoring is another important concept in some theoretical models of learner use of L2 knowledge. According to Krashen (1982), the Monitor is a component of an L2 learner’s language processing device that uses knowledge gained from language learning to observe and regulate the learner’s own L2 production, checking for accuracy and adjusting language production when necessary.
Perhaps certain psychological characteristics constrain language processing. One area of research is the role of memory. Williams (1999) conducted a study in which he found some positive correlation between verbatim memory functioning and grammar learning success for his subjects. This suggests that individuals with less short-term memory capacity might have a limitation in performing cognitive processes for organization and use of linguistic knowledge.
Attention is another characteristic that some believe to have a role in determining the success or failure of language processing. Schmidt (1990) states that although explicit metalinguistic knowledge of a language is not always essential for acquisition, the learner must be aware of L2 input in order to gain from it. In his “noticing hypothesis,” Schmidt posits that learners must notice the ways in which their interlanguage structures differ from target norms. This noticing of the gap allows the learner’s internal language processing to restructure the learner’s internal representation of the rules of the L2 in order to bring the learner’s production closer to the target. In this respect, Schmidt’s understanding is consistent with the ongoing process of rule formation found in emergentism and connectionism.
Restructuring Second Language Knowledge Structures
Finally, some theorists and researchers have contributed to the cognitive approach to second language acquisition by increasing understanding of the ways L2 learners restructure their interlanguage knowledge systems to be in greater conformity to L2 structures. Processability theory states that learners restructure their L2 knowledge systems in an order of which they are capable at their stage of development (Pienemann, 1998). For instance, In order to acquire the correct morphological and syntactic forms for English questions, learners must transform declarative English sentences. They do so by a series of stages, consistent across learners. Clahsen (1984) proposed that certain processing principles determine this order of restructuring. Specifically, he stated that learners first, maintain declarative word order while changing other aspects of the utterances, second, move words to the beginning and end of sentences, and third, move elements within main clauses before subordinate clauses.
In addition, when learners experience significant restructuring in their L2 systems, they sometimes show what has been termed U-shaped behavior. For instance, Lightbrown (1983) showed that a group of English language learners moved, over time, from accurate usage of the “-ing” present progressive morpheme, to incorrectly omitting it, and finally, back to correct usage. This is explained by theorizing that learners first acquired the “-ing” form as a chunk, second, lost control of this form as their knowledge system was disrupted by expanding understandings of the tense and aspect systems of English, and third, returned to correct usage upon gaining greater control of these linguistic characteristics and forms. These data provide evidence that learners were initially producing output based on rote memory of individual words containing the present progressive morpheme. However, in the second stage their systems apparently contained the rule that they should use the bare infinitive form to express present action, without a separate rule for the use of “-ing.” Finally, their systems did contain such a rule.
In the preceding sections, I have introduced the principle ideas in the cognitive approach to second language acquisition. This approach has contributed to a greater understanding of how learners form internal language systems of information, use those systems in L2 processing, and restructure those systems as they gain greater L2 proficiency.
Language transfer
Language transfer typically refers to the learner's trying to apply rules and forms of the first language into the second language. The term can also include the transfer of features from one additional language to another (such as from a second to a third language), although this is less common. Contrastive analysis, discussed above, sought to predict all learner errors based on language transfer. As subsequent research in error analysis and interlanguage structure showed, this project was flawed: most errors are not due to transfer, but to faulty inferences about the rules of the target language. Transfer is an important factor in language learning at all levels. Typically learners begin by transferring sounds (phonetic transfer) and meanings (semantic transfer), as well as various rules including word order and pragmatics. As learners progress and gain more experience with the target language, the role of transfer typically diminishes. In the UG-based framework (see Linguistic universals below), "language transfer" specifically refers to the linguistic parameter settings defined by the language universal. Thus, "language transfer" is defined as the initial state of second language acquisition rather than its developmental stage.


Linguistic universals
Research on universal grammar (UG) has had a significant effect on SLA theory. In particular, scholarship in the interlanguage tradition has sought to show that learner languages conform to UG at all stages of development. A number of studies have supported this claim, although the evolving state of UG theory makes any firm conclusions difficult.

A key question about the relationship of UG and SLA is: is the language acquisition device posited by Chomsky and his followers still accessible to learners of a second language? Research suggests that it becomes inaccessible at a certain age (see Critical Period Hypothesis), and learners increasingly depended on explicit teaching (see pedagogical effects above, and age below). In other words, although all of language may be governed by UG, older learners might have great difficulty in gaining access to the target language's underlying rules from positive input alone. Another key question is the degree to which findings on the conformity of learner language to UG can be replicated with learners who are not alphabetically literate.
Individual variation
Research on variation between individual learners seeks to address the question: Why do some learners do better than others? A flurry of studies in the 1970s, often labelled the "good language learner studies", sought to identify the distinctive factors of successful learners. Although those studies are now widely regarded as simplistic, they did serve to identify a number of factors affecting language acquisition. More detailed research on many of these specific factors continues today.
Language aptitude
Tests of language aptitude have proven extremely effective in predicting which learners will be successful in learning. However, considerable controversy remains about whether language aptitude is properly regarded as a unitary concept, an organic property of the brain, or as a complex of factors including motivation and short-term memory. Research has generally shown that language aptitude is quite distinct from general aptitude or intelligence, as measured by various tests, and is itself fairly consistently measurable by different tests.
Language aptitude research is often criticized for being irrelevant to the problems of language learners, who must attempt to learn a language regardless of whether they are gifted for the task or not. This claim is reinforced by research findings that aptitude is largely unchangeable. In addition, traditional language aptitude measures such as the Modern Language Aptitude Test strongly favor decontextualized knowledge of the sort used in taking tests, rather than the sort used in conversation. For this reason little research is carried out on aptitude today. However, operators of selective language programs such as the United States Defense Language Institute continue to use language aptitude testing as part of applicant screening.
Age
It is commonly believed that children are better suited to learn a second language than are adults. However, general second language research has failed to support the critical period hypothesis in its strong form (i.e., the claim that full language acquisition is impossible beyond a certain age). According to Linda M. Espinosa, especially in the United States the number of children growing up with a home language that is not English but Spanish is constantly increasing.[1] Therefore these children have to learn the English language before kindergarten as a second language. It is better to dispose young children to maintain both, their home language and their second language. Cultivating their home language, the child creates their own cultural identity and becomes aware of their roots. This fact leads to the question whether having the ability to speak two languages helps or harms young children. Research shows that the acquisition of a second language in early childhood confers several advantages, especially a greater awareness of linguistic structures. Furthermore it is advantageous for young children to grow up bilingually because they do not need to be taught systematically but learn languages intuitively. How fast a child can learn a language depends on several personal sfactors, such as interest and motivation, and its learning environment. Communication should be facilitated rather than a child should be forced to learn a language with strict rules. Education in early childhood can lead to an effective educational achievement for children from various cultural environments.
Another aspect that is worth considering is that bilingual children are often doing code switching which does not mean that the child is not able to separate the languages. The reason for code switching is the child's lack of vocabulary in a certain situation. The acquisition of a second language in early childhood broadens the children's minds and enriches them more that it harms them. Thus they are not only able to speak two languages in spite of being very young but they also acquire knowledge about the different cultures and environments. It is possible that one language can dominate. This depends on how much time is spent on learning each language.[1]
Strategy use
The effective use of strategies has been shown to be critical to successful language learning, so much so that Canale and Swain (1980) included "strategic competence" among the four components of communicative competence. Research here has also shown significant pedagogical effects. This has given rise to "strategies-based instruction."
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. Learners (and native speakers) use communicative strategies to get meaning across even when they lack access to the correct language: for example, by using pro-forms like "thing", or non-spoken means such as mime. Communicative strategies may not have any direct bearing on learning, and some strategies such as avoidance (not using a form with which one is uncomfortable) may actually hinder learning.
Learners from different cultures use strategies in different ways (Hadzibeganovic & Cannas, 2009), as a research tradition led by Rebecca Oxford has demonstrated. Related to this are differences in strategy use between male and female learners. Numerous studies have shown that female learners typically use strategies more widely and intensively than males; this may be related to the statistical advantage which female learners enjoy in language learning.
Affective factors
Affective factors relate to the learner's emotional state and attitude toward the target language. Research on affect in language learning is still strongly influenced by Bloom's taxonomy, which describes the affective levels of receiving, responding, valuing, organization, and self-characterization through one's value system. It has also been informed in recent years by research in neurobiology and neurolinguistics.
Affective Filter Furthermore, researchers believe that language learners all possess an affective filter which affects language acquisition. If a student possesses a high filter they are less likely to engage in language learning because of shyness, concern for grammar or other factors. Students possessing a lower affective filter will be more likely to engage in learning because they are less likely to be impeded by other factors. The affective filter is an important component of second language learning.

Anxiety
Although some continue to propose that a low level of anxiety may be helpful, studies have almost unanimously shown that anxiety damages students' prospects for successful learning. Anxiety is often related to a sense of threat to the learner's self-concept in the learning situation, for example if a learner fears being ridiculed for a mistake.
Personality Factors
Second language acquisition is defined as the learning and adopting of a language that is not your native language. Studies[vague] have shown that extroverts (or unreserved and outgoing people) acquire a second language better than introverts (or shy people).
One particular study done by Naiman reflected this point. The subjects were 72 Canadian high school students from grades 8, 10 and 12 who were studying French as a second language.
Naiman gave them all questionnaires to establish their psychological profiles, which also included a French listening test and imitation test. He found that approximately 70% of the students with the higher grades (B or higher) would consider themselves extroverts.
Extroverts will be willing to try to communicate even if they are not sure they will succeed. Two scientists, Kinginger and Farrell, conducted interviews with U.S. students after their study abroad program in France in 2003. They found that many of the students would avoid interaction with the native speakers at all costs, while others jumped at the opportunity to speak the language. Those who avoided interaction were typically quiet, reserved people, (or introverts).
Logically, anxiety will cause students not to try and advance their skills, especially when they feel they are under pressure. Just the lack of practice will make introverts less likely to fully acquire the second language.
Motivation
The role of motivation in SLA has been the subject of extensive scholarship, closely influenced by work in motivational psychology. Motivation is internally complex, and Dörnyei (2001a, p. 1) begins his work by stating that "strictly speaking, there is no such thing as motivation." There are many different kinds of motivation; these are often divided into types such as integrative or instrumental, intrinsic or extrinsic. Intrinsic motivation refers to the desire to do something for an internal reward. Most studies have shown it to be substantially more effective in long-term language learning than extrinsic motivation, for an external reward such as high grades or praise. Integrative and instrumental orientations refer to the degree that a language is learned "for its own sake" (integratively) or for instrumental purposes. Studies have not consistently shown either form of motivation to be more effective than the other, and the role of each is probably conditioned by various personality and cultural factors.
Some research has shown that motivation correlates strongly with proficiency, indicating both that successful learners are motivated and that success improves motivation. Thus motivation is not fixed, but is strongly affected by feedback from the environment. Accordingly, the study of motivation in SLA has also examined many of the external factors discussed above, such as the effect of instructional techniques on motivation. An accessible summary of this research can be found in Dörnyei (2001a).
In their research on Willingness to communicate, MacIntyre et al. (1998) have shown that motivation is not the final construct before learners engage in communication. In fact, learners may be highly motivated yet remain unwilling to communicate.
The European Union Lifelong learning programme has funded a project to research and build a set of best practices to motivate adult language learners, called Don't Give Up
Understanding SLA
The systematic modelling of SLA is concerned with the question: What are the most important overall factors in language acquisition? Models of SLA have played an important role in laying out directions for future research, and also for informing practice in language teaching.
Different models of SLA have focused on different aspects of SLA and general linguistic research. For example, Schumann's Acculturation Model, which viewed second language acquisition as just one part of adapting to a new culture, emphasized findings related to language socialization. Krashen's Monitor Model prioritized research on input and affective factors. Long's Interaction Hypothesis took a social constructivist view of research on input. Caleb Gattegno based The Silent Way on the principle of the education of awareness. No single model of SLA has gained wide acceptance. Given that the field is complex and interdisciplinary, few scholars expect that any model will do so in the foreseeable future.


Concepts of ability
Numerous notions have been used to describe learners' ability in the target language. The first such influential concept was the competence-performance distinction introduced by Chomsky. This distinguishes competence, a person's idealized knowledge of language rules, from performance, the imperfect realization of these rules. Thus, a person may be interrupted and not finish a sentence, but still know how to make a complete sentence. Although this distinction has become fundamental to most work in linguistics today, it has not proven adequate by itself to describe the complex nature of learners' developing ability.
The notion of communicative competence was first raised by Dell Hymes in 1967, reacting against the perceived inadequacy of Chomsky's distinction between linguistic competence, and has proven extremely popular in SLA research. It broadens the notion of the kind of rules that competence can include. Whereas Chomsky treated competence as primarily grammatical, communicative competence embraces all of the forms of knowledge that learners must have in order to communicate effectively.
A closely related concept is language proficiency. Proficiency is usually distinguished from competence, which refers to knowledge: "proficiency refers to the learner's ability to use this knowledge in different tasks" (Ellis, 1994, p. 720). Because any test of competence is a task of some sort, it may be argued that all measures of competence are in effect measuring some form of proficiency.
Both proficiency and competence are internally complex; they do not reflect a single attribute, but many different forms of knowledge in complex interrelationship. Research, such as much of that discussed here, requires some unitary concept of ability, but it has been clearly shown that different aspects of language ability progress at vary different rates. For example, Kasper and Rose (2002) review numerous studies of the complex relationship between grammatical and pragmatic proficiency. The measurement of language ability, although necessary for both research and teaching, is inevitably problematic.
References
• Allwright, D. & Hanks, J. (2009). The Developing Language Learning: An Introduction to Exploratory Practice. Basingstoke: Palgrave MacMillan.
• Anderson, J. R. (1992). Automaticity and the ACT* theory. American Journal of Psychology, 105, 165–180.
• Bialystok, E., & Smith, M. S. (1985). Interlanguage is not a state of mind: An evaluation of the construct for second-language acquisition. Applied Linguistics, 6(2), 101-117.
• Bialystok, E. (1994). Analysis and control in the development of second language proficiency. Studies in Second Language Acquisition, 16(2), 157-168.
• Canale, M. & Swain, M. (1980). Theoretical bases of communicative approaches to second language teaching and testing. Applied Linguistics 1(1): 1-47.
• Castro-Caldas, A., Petersson, A., Reis, S., Stone-Elander, & Ingvar, M. (1998). The illiterate brain: Learning to read and write during childhood influences the functional organization of the adult brain. Brain, 121, 1053-1063.
• Christiansen, M. H., & Chater, N. (2001). Connectionist psycholinguistics: Capturing the empirical data. Trends in Cognitive Sciences, 5(2), 82-88.
• Clahsen, H. (1984) The acquisition of German word order: a test case for cognitive approaches to second language acquisition. In R. Andersen (ed.), Second Languages. Rowley, MA: Newbury House, 219–42.
• Corder, S. P. (1967). The significance of learners' errors. International Review of Applied Linguistics, 5, 160-170.
• DeKeyser, R. M. (1997). Beyond explicit rule learning: Automatizing second language morphosyntax. Studies in Second Language Acquisition, 19, 195–222.
• Dewaele, J. and Furnham, A. "Personality and Individual Differences." Personality and Speech Production: A Pilot Study of Second Language Learners 28 (2000): 355-365
• Dörnyei, Z. (2001a). "New themes and approaches in second language motivation research." Annual Review of Applied Linguistics, 21, 43-59.
• Doughty, C., & Williams, J. (Eds.). (1998). Focus on Form in Classroom Second Language Acquisition. Cambridge: Cambridge University Press.
• Ellis, N. (2002). Frequency effects in language processing. Studies in Second Language Acquisition, 24(2), 143-188.
• Ellis, R. (2002). Does form-focused instruction affect the acquisition of implicit knowledge? Studies in Second Language Acquisition, 24(2), 223-236.
• Ellis, R. (2005). Measuring implicit and explicit knowledge of a second language: A psychometric study. Studies in Second Language Acquisition, 27(2), 141-172.
• Espinosa, L.M.Second language acquisition in early childhood.In New, R. & Cochran, M.(Eds.).Early Childhood Education. Westport,CT: Greenwood Publishing Group.6
• Fasold, R., & Preston, D. (2007). The psycholinguistic unity of inherent variability: Old Occam whips out his razor. In R. Bayley & C. Lucas (Eds.), Sociolinguistic Variation: Theory, methods, and applications (pp. 45–69). Cambridge: Cambridge University Press.
• Hadzibeganovic, Tarik, & Cannas, Sergio A. (2009). A Tsallis' statistics based neural network model for novel word learning. Physica A, 388(5), 732-746.
• Hulstijn, J. H. (2005). Theoretical and empirical issues in the study of implicit and explicit second-language learning. Studies in Second Language Acquisition, 27(2), 129-140.
• Kasper, G. and Rose, K.R. (2002). Pragmatic Development in a Second Language. Language Learning, 52, Supplement 1.
• Krashen, S. (1982). Principles and Practice in Second Language Acquisition. London: Pergamon.
• Lightbrown, P. (1983). Exploring relationships between developmental and instructional sequences in L2 acquisition. In H. Seliger and M. H. Long (Eds.), Classroom Oriented Research in Second Language Acquisition (pp. 217–243). Rowley, MA: Newbury House.
• Lightbown, P. (1990) Process-product research on second language learning in classrooms cited in 'The study of SLA' (Rod Ellis)
• Lyster, R., & Ranta, L. (1997). Corrective feedback and learner uptake: Negotiation of form in communicative classrooms. Studies in Second Language Acquisition, 19, 37-66.
• Lyster, R., & Mori, H. (2006). Interactional feedback and instructional counterbalance. Studies in Second Language Acquisition, 28, 269-300.
• MacIntyre, P.D., Clément, R., Dörnyei, Z., & Noels, K.A. (1998). Conceptualizing willingness to communicate in an L2: A situational model of L2 confidence and affiliation. The Modern Language Journal, 82 (4), 545-562.
• MacWhinney, B., Bates, E., & Kliegl, R. (1984). Cue validity and sentence interpretation in English, German, and Italian. Journal of Verbal Learning and Verbal Behavior. 23(2), 127-150.
• Naiman, N., Frohlich, M., and Stern, H. "The Good Language Learner: A Report." Ontario Institute for Studies in Education (1975)
• Pienemann, M. (1998) Language Processing and Second Language Development: Processability Theory. Amsterdam: John Benjamins.
• Rampton, B. (1995). Crossing: Language and Ethnicity Among Adolescents. London: Longman.
• Reis, A., & Castro-Caldas, A. (1997). Illiteracy: A case for biased cognitive development. Journal of the International Neuropsychological Society, 3, 444-450.
• Seidner, S. S.(1982). Ethnicity, Language, and Power from a Psycholinguistic Perspective. Bruxelles: Centre de recherche sur le pluralinguisme.
• Selinker, L. (1972). Interlanguage. International Review of Applied Linguistics, 10, 209-241.
• Selinker, L., & Douglas, D. (1985). Wrestling with 'context' in interlanguage theory. Applied Linguistics, 6, 190-204.
• Tarone, E. (2009). A sociolinguistic perspective on interaction in SLA, in A. Mackey & C. Polio (Eds.), Multiple Perspectives on Interaction: Second language research in honor of Susan M. Gass. (pp. 41–56). New York: Routledge.
• Tarone, E., Bigelow, M. & Hansen, K. (2009). Literacy and Second Language Oracy. Oxford: Oxford University Press.[1]
• Tarone, E., & Liu, G.-q. (1995). Situational context, variation and second-language acquisition theory. In G. Cook & B. Seidlhofer (Eds.), Principles and Practice in the Study of Language and Learning: A Festschrift for H.G. Widdowson (pp. 107–124). Oxford: Oxford University Press.
• Tarone, E., & Swierzbin, B. (2009). Exploring Learner Language. Oxford: Oxford University Press.[2]
• Ullman, M. T. (2001). The declarative/procedural model of lexicon and grammar. Journal of Psycholinguistic Research, 30(1), 37-69.
• Williams, J. (1999) Memory, attention and inductive learning. Studies in Second Language Acquisition, 21, 1–48.
Further reading
• Cook, V. (2008). Second Language Learning and Language Teaching (4th ed). London: Hodder Arnold.
• Ellis, R. (2008). The Study of Second Language Acquisition (2nd ed.). Oxford: Oxford University Press.
• Ellis, Rod. (2007). Educational Settings and Second Language Learning. Volume 9 Asian EFL Journal. [3]
• Ellis, Rod. (2005). Principles of Instructed Language Learning. Volume 7 Asian EFL Journal. [4]
• 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 [5]
• Long, Michael H. (1980's) authored several papers on the Interaction hypothesis (Rod Ellis's overview)}}
• Ellis, Rod (1991), The Interaction Hypothesis A critical evaluation, pp. 37, http://www.eric.ed.gov/ERICWebPortal/contentdelivery/servlet/ERICServlet?accno=ED338037 - 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 [6]
• 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.[7]
• Robertson, P. & Nunn, R. (2007). The Study of Second Language Acquisition in the Asian Context [8]
• White, L. (2003). Second Language Acquisition and Universal Grammar. Cambridge: Cambridge University Press.
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