Instruction and Assessment · 13 min read
Theories of Language Acquisition
Overview of Language Acquisition
Language acquisition refers to the process by which humans learn languages. This process differs depending on whether the language is a first language (L1) acquired in childhood or a second/additional language (L2) learned later. Both processes have been extensively studied, yielding theories that inform language teaching practice.
First language acquisition is the natural process by which children acquire their native language(s) through exposure and interaction, without formal instruction. This process is remarkably consistent across cultures and languages, with children reaching similar milestones at similar ages.
Second language acquisition (SLA) refers to learning any language after the first. This includes both naturalistic acquisition through immersion and instructed acquisition in classroom settings. SLA research examines how learners develop competence in additional languages and what factors affect this process.
Understanding both L1 and L2 acquisition helps teachers appreciate what learners bring to the classroom, set realistic expectations, and design effective instruction.
| Theory | Key figure | Central idea | Classroom implication |
|---|---|---|---|
| Behaviorism | B. F. Skinner | Language is habit formation through stimulus, response, and reinforcement | Audio-lingual drills and pattern practice |
| Nativism / Universal Grammar | Noam Chomsky | Humans have an innate capacity for language | Errors are developmental; rich input matters more than drilling |
| Input Hypothesis | Stephen Krashen | Acquisition comes from comprehensible input slightly beyond current level (i + 1); a high affective filter blocks it | TPR, TPRS, extensive reading and listening, low-anxiety classrooms |
| Interaction Hypothesis | Michael Long | Negotiation of meaning makes input comprehensible and draws attention to form | Information-gap and jigsaw tasks, pair and group work |
| Output Hypothesis | Merrill Swain | Producing language pushes learners to notice gaps in their knowledge | Pushed output in speaking and writing with feedback |
| Sociocultural Theory | Lev Vygotsky | Learning is mediated by social interaction within the zone of proximal development | Scaffolding, collaborative tasks, peer support |
Behaviorist Theory
Behaviorism dominated psychology and language learning theory in the mid-twentieth century. B.F. Skinner's "Verbal Behavior" (1957) applied behaviorist principles to language acquisition.
Core Principles
Behaviorism views language learning as habit formation through stimulus-response-reinforcement patterns. According to this view:
Language is a set of habits acquired through imitation and repetition.
Children learn language by imitating adult speech and receiving reinforcement (praise, successful communication) for correct productions.
Errors result from interference of old habits with new learning.
Learning occurs through conditioning, with correct responses strengthened and incorrect ones extinguished.
Implications for Teaching
Behaviorist theory led to the Audiolingual Method, which dominated language teaching in the 1950s and 1960s. Key features included:
Emphasis on oral skills before reading and writing.
Pattern drills to establish correct habits.
Memorization of dialogues.
Immediate error correction to prevent bad habit formation.
Avoidance of the native language in instruction.
Contrastive analysis to predict and address interference errors.
Limitations
Noam Chomsky's review of Skinner's work (1959) devastated behaviorist accounts of language acquisition. Chomsky argued that:
The language input children receive (the "poverty of the stimulus") is insufficient to explain the complex grammatical knowledge they acquire.
Children acquire language with remarkable speed and uniformity despite varying input and reinforcement.
Language acquisition differs fundamentally from other types of learning.
While pure behaviorism is no longer accepted, some behaviorist insights remain relevant. Practice and repetition do play roles in language learning, particularly in developing automaticity. Error correction has value when appropriately timed and delivered.
Nativist Theory
Nativist theory, associated primarily with Noam Chomsky, proposes that humans are biologically endowed with an innate capacity for language acquisition.
Universal Grammar
Chomsky proposed that humans possess an innate Universal Grammar (UG), a set of principles and parameters that constrain possible human languages. According to this theory:
All human languages share fundamental structural properties despite surface differences.
Children are born with UG already in place, predisposing them to acquire language.
Language acquisition involves setting parameters based on input from the specific language being acquired.
The Language Acquisition Device (LAD) is a hypothetical mental module dedicated to language learning.
Evidence for Innateness
Several observations support nativist claims:
The universality of language acquisition across cultures and environments.
The speed and ease with which children acquire complex grammatical systems.
The existence of critical or sensitive periods after which full native-like acquisition becomes difficult.
The specific nature of children's errors, which follow predictable patterns suggesting rule-based rather than random processing.
Cases of language acquisition despite impoverished input (deaf children of hearing parents developing gestural communication systems).
Critical Period Hypothesis
The Critical Period Hypothesis proposes that there is a biologically determined window during which language acquisition can occur naturally and completely. After this period (roughly puberty), acquisition becomes more difficult and is unlikely to result in native-like proficiency.
Evidence for critical periods includes:
Cases of children deprived of language input (feral or severely neglected children) who fail to fully acquire language after the critical period.
Differences in ultimate attainment between child and adult L2 learners.
Changes in brain plasticity with age.
However, the critical period concept remains debated. Some researchers propose sensitive periods rather than absolute cutoffs, and individual variation is substantial.
Implications for L2 Learning
Nativist theory raises questions about L2 acquisition:
Is UG still accessible to adult L2 learners?
If so, why do adults typically fail to achieve native-like proficiency?
What role does L1 knowledge play in constraining L2 acquisition?
Different positions exist on these questions, ranging from full access to no access to partial access views.
Interactionist Theory
Interactionist theories emphasize the role of social interaction and meaningful communication in language acquisition. Rather than viewing acquisition as purely innate or purely environmental, interactionists see it as emerging from the interplay between cognitive capacities and communicative experiences.
Input Hypothesis
Stephen Krashen's Input Hypothesis (part of his broader Monitor Model) proposes that language acquisition occurs when learners receive comprehensible input slightly beyond their current level (i+1). Key claims include:
Acquisition requires meaningful, comprehensible input.
Conscious learning (explicit rule knowledge) is separate from acquisition and has limited use.
Affective factors (motivation, anxiety, self-confidence) filter input and affect acquisition.
Krashen distinguished between acquisition (unconscious, implicit) and learning (conscious, explicit), arguing that only acquisition leads to fluent, automatic language use.
Interaction Hypothesis
Michael Long's Interaction Hypothesis built on Krashen's work by emphasizing the role of conversational interaction. Long argued that:
Interaction makes input comprehensible through negotiation of meaning.
When communication breaks down, speakers modify their language (clarification requests, confirmation checks, comprehension checks, repetitions).
These modifications provide learners with evidence about language forms while maintaining meaningful communication.
Interaction creates opportunities for learners to notice gaps between their interlanguage and target language.
Output Hypothesis
Merrill Swain's Output Hypothesis complemented input-focused theories by arguing that producing language (output) also contributes to acquisition. Output:
Pushes learners to process language more deeply than comprehension alone requires.
Forces learners to move from semantic processing to syntactic processing.
Allows learners to test hypotheses about language and receive feedback.
Promotes noticing of gaps in linguistic knowledge.
Develops automaticity through practice.
Sociocultural Theory
Lev Vygotsky's sociocultural theory, though not originally about language acquisition, has been influential in L2 research. Key concepts include:
The Zone of Proximal Development (ZPD), the distance between what learners can do independently and what they can do with assistance. Learning occurs within the ZPD through scaffolded interaction.
Mediation through cultural tools, including language itself. Language is both the object of learning and the means through which learning occurs.
The social origins of mental processes. Higher cognitive functions develop first in social interaction before becoming internalized.
Private speech and inner speech as tools for self-regulation and cognitive processing.
Activity theory, examining how learning occurs within goal-directed activities in specific sociocultural contexts.
Implications for Teaching
Interactionist theories suggest that teachers should:
Provide abundant comprehensible input in meaningful contexts.
Create opportunities for meaningful interaction in the target language.
Design tasks that require negotiation of meaning.
Encourage output and provide supportive feedback.
Scaffold learner performance within the ZPD.
Consider affective factors that may impede acquisition.
Create low-anxiety environments conducive to risk-taking.
Cognitive Theories
Cognitive theories view language acquisition as a type of learning subject to general cognitive principles rather than a specialized innate faculty.
Information Processing
Information processing models apply cognitive psychology concepts to language learning:
Working memory limitations constrain what can be processed at any moment.
Learning involves moving from controlled to automatic processing through practice.
Declarative knowledge (knowing that) can become procedural knowledge (knowing how) through practice.
Skill acquisition theory, drawing on John Anderson's ACT model, describes stages from cognitive (understanding) through associative (practice) to autonomous (automatization).
Connectionism
Connectionist or emergentist approaches model language learning as pattern extraction through neural networks:
Language knowledge emerges from processing patterns in input rather than from innate rules.
Frequency and distributional patterns in input shape learning.
Neural network models can simulate aspects of language acquisition.
There is no need to posit innate language-specific mechanisms; general learning mechanisms suffice.
Usage-Based Theories
Usage-based approaches, associated with Michael Tomasello and others, propose that:
Language is learned through general cognitive processes including intention-reading, pattern-finding, and analogy.
Constructions (form-meaning pairings of varying sizes and abstraction) are the basic units of language.
Frequency of exposure drives learning.
Categories and rules are abstracted from specific instances rather than innate.
Children learn language through engagement in communicative activities with more skilled users.
Implications for Teaching
Cognitive theories suggest:
Drawing learner attention to target forms through input enhancement, explicit instruction, or other means.
Providing sufficient practice for procedural development and automatization.
Ensuring high-frequency exposure to target patterns.
Presenting language in meaningful contexts where form-meaning connections are clear.
Addressing the processing demands placed on learners.
Building from exemplars toward productive patterns.
Monitor Model and Related Hypotheses
Stephen Krashen's Monitor Model, developed in the 1970s and 1980s, has been highly influential in language teaching despite theoretical criticisms.
The Five Hypotheses
The Acquisition-Learning Hypothesis distinguishes unconscious acquisition from conscious learning. Acquisition occurs through meaningful communication; learning involves explicit attention to rules. Only acquisition leads to spontaneous, fluent language use.
The Monitor Hypothesis proposes that learned knowledge serves only as a monitor or editor for output generated by the acquired system. Using the monitor requires time, focus on form, and knowledge of the rule.
The Input Hypothesis states that acquisition occurs through comprehensible input containing structures slightly beyond the learner's current level (i+1). Speaking emerges naturally; it should not be forced.
The Affective Filter Hypothesis proposes that emotional factors (anxiety, motivation, self-confidence) act as a filter that can block input from reaching the acquisition device.
Implications for Teaching
Krashen's theories led to the Natural Approach and influenced communicative language teaching:
Maximize comprehensible input through extensive reading and listening.
Delay production until learners are ready.
Focus on meaning rather than form.
Create low-anxiety learning environments.
Do not expect immediate benefits from grammar instruction.
Criticisms
Critics have challenged Krashen's hypotheses on various grounds:
The acquisition-learning distinction is difficult to operationalize and test.
The i+1 concept is too vague to be useful.
The model cannot explain observed benefits of explicit instruction.
The natural order may reflect instruction and frequency rather than innate ordering.
Despite criticisms, Krashen's work has positively influenced teaching by emphasizing meaningful communication, extensive input, and attention to affect.
Interlanguage Theory
Larry Selinker introduced the concept of interlanguage (1972) to describe the systematic language system that learners construct during acquisition.
Characteristics of Interlanguage
Interlanguage is systematic rather than random. Learner errors follow patterns reflecting an internal grammar.
Interlanguage is dynamic, constantly evolving as learners receive input and revise hypotheses.
Interlanguage is permeable, open to influence from both L1 and L2.
Interlanguage reflects cognitive processes including overgeneralization, simplification, and transfer.
Developmental Sequences
Research has identified developmental sequences for various structures:
Negation develops through stages (external negation, internal negation, target-like negation).
Question formation follows predictable patterns.
Morpheme acquisition shows ordering effects.
These sequences appear relatively fixed, though instruction may affect the rate of progress through stages.
Fossilization
Fossilization refers to the cessation of interlanguage development in certain areas despite continued exposure and motivation. Features that fossilize become permanent parts of the learner's system.
Fossilization is particularly common for phonology (accent) but can affect any aspect of language. Factors associated with fossilization include age, communicative success despite errors, and lack of feedback.
Implications for Teaching
Interlanguage research suggests:
Errors are natural and systematic, not random failures.
Developmental sequences may limit what can be taught at any given time.
Teachers should assess where learners are in developmental sequences.
Some errors may be resistant to instruction if learners are not developmentally ready.
Complete elimination of errors may be unrealistic; fossilization is common.
Additional Factors in Second Language Acquisition
Age
Age affects L2 acquisition in complex ways:
Younger learners typically achieve more native-like pronunciation and grammar in the long term.
Older learners often learn more quickly initially due to cognitive advantages.
Age effects are strongest for phonology, moderate for syntax, and weakest for vocabulary.
Individual variation is substantial; some adults achieve near-native proficiency.
Aptitude
Language learning aptitude includes abilities such as:
Phonemic coding ability (discriminating and encoding sounds).
Grammatical sensitivity (recognizing grammatical functions).
Inductive learning ability (inferring rules from examples).
Rote learning ability (memorizing associations).
Aptitude predicts success in traditional instructed settings but may be less relevant in naturalistic acquisition.
Motivation
Motivation is consistently associated with L2 achievement:
Integrative motivation involves desire to communicate with and become like target language speakers.
Instrumental motivation involves practical goals like career advancement.
Both types can support learning; the relative importance varies by context.
Motivation is dynamic, fluctuating over time and affected by experiences.
The L2 Motivational Self System (Dörnyei) emphasizes ideal L2 self images as motivating forces.
Learning Strategies
Successful learners employ various strategies:
Cognitive strategies (analyzing, reasoning, summarizing).
Metacognitive strategies (planning, monitoring, evaluating).
Social strategies (seeking interaction, asking questions).
Affective strategies (managing anxiety, encouraging oneself).
Strategy instruction can improve learning, particularly for less successful learners.
Individual Differences
Learners differ in learning styles, personality factors (extroversion, risk-taking, tolerance of ambiguity), working memory capacity, and many other dimensions. Effective teaching accommodates this diversity.
Implications for Classroom Instruction
Research on language acquisition suggests several principles for classroom practice:
Provide abundant comprehensible input through listening, reading, and meaningful interaction.
Create opportunities for meaningful output and interaction.
Balance attention to meaning with attention to form.
Design instruction that is sensitive to developmental sequences.
Recognize the role of the first language as both resource and source of transfer.
Address individual differences in aptitude, motivation, and learning style.
Create supportive, low-anxiety learning environments.
Set realistic expectations given age-related differences.
View errors as evidence of developing interlanguage rather than failures.
Integrate explicit instruction with communicative practice.
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