Second Language Acquisition (SLA) – Theories, Stages, Factors | ELT, PGTRB Notes

Second Language Acquisition (SLA) – Meaning, Theories, Stages & Factors

Second Language Acquisition (SLA) is the process by which people learn a language other than their mother tongue. It studies how learners acquire, develop and use a second language (L2) in natural or classroom settings.

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1. What is Second Language Acquisition?

• First Language (L1) – the mother tongue learned naturally in childhood.
• Second Language (L2) – any additional language learned after L1.

SLA is concerned with:

• stages of learning L2
• errors and interlanguage
• influence of L1
• the role of input, interaction and output
• psychological and social factors affecting learning

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2. Acquisition vs Learning

Many scholars (especially Stephen Krashen) distinguish between:

• Acquisition – subconscious, natural development (like children learning L1).
• Learning – conscious knowledge of rules (grammar study, classroom teaching).

Good L2 development often involves both processes working together.

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3. Major Theories of Second Language Acquisition

3.1 Behaviorist Theory

• Language learning as habit formation.
• Based on stimulus–response–reinforcement.
• Audio-lingual method, drills, repetition.
• L1 habits interfere with L2 (negative transfer).

3.2 Innatist / Nativist Theory (Chomsky)

• Humans are born with a Language Acquisition Device (LAD).
• There is an inborn Universal Grammar (UG).
• SLA is partly guided by innate principles, but influenced by L1 and input.

3.3 Krashen’s Monitor Model

Krashen proposed five main hypotheses:

1. Acquisition–Learning Hypothesis
   Acquisition (subconscious) ≠ Learning (conscious grammar study).
2. Monitor Hypothesis
   Learned knowledge acts as a monitor to edit output, not to create it.
3. Natural Order Hypothesis
   L2 structures are acquired in a predictable order, not necessarily the order taught.
4. Input Hypothesis
   Learners acquire language when they receive comprehensible input at a slightly higher level than their current one (i+1).
5. Affective Filter Hypothesis
   Low anxiety, high motivation and confidence lower the affective filter and help acquisition.

3.4 Cognitive Theory

• Language learning is like learning any other complex skill.
• Involves attention, memory, practice and automatization.
• Learners move from controlled to automatic processing.

3.5 Interaction Hypothesis (Long)

• Comprehensible input alone is not enough.
• Interaction (negotiation of meaning, clarification requests, feedback) helps acquisition.

3.6 Socio-cultural Theory (Vygotsky)

• Language learning is socially constructed.
• Zone of Proximal Development (ZPD) – learners achieve more with support.
• Scaffolding from teachers/peers helps L2 growth.

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4. Stages of Second Language Acquisition

Commonly observed stages:

1. Pre-production (Silent Period) – Learner listens, understands some words, but speaks little or not at all.
2. Early Production – Uses one- or two-word phrases, memorised chunks, yes/no answers.
3. Speech Emergence – Uses simple sentences, makes many mistakes but can communicate basic ideas.
4. Intermediate Fluency – Longer sentences, better grammar, begins to express opinions and connect ideas.
5. Advanced Fluency – Near-native proficiency in many contexts, but still may show traces of L1.

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5. Interlanguage

Interlanguage is the learner’s internal language system that is neither L1 nor fully L2, but something in between.

Features of Interlanguage

• Systematic, rule-governed.
• Contains errors that show progress, not failure.
• Changes over time as the learner receives more input and feedback.
• Shows transfer from L1 and influence of teaching.

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6. Errors and Error Analysis

In SLA, errors are seen as natural and useful.

• Interlingual errors – influence of L1.
• Intralingual errors – overgeneralization of L2 rules.

Error Analysis helps teachers understand learner difficulties and improve teaching methods.

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7. Factors Influencing Second Language Acquisition

7.1 Learner-related Factors

• Age – children vs adults.
• Motivation – instrumental (marks, job) vs integrative (joining the culture).
• Attitude towards L2 and culture.
• Aptitude – natural ability to learn languages.
• Personality – introvert/extrovert, risk-taking.

7.2 Linguistic Factors

• Similarity/difference between L1 and L2.
• Transfer (positive and negative).
• Complexity and frequency of L2 structures.

7.3 Social Factors

• Exposure to L2 environment.
• Opportunities for interaction.
• Classroom vs natural setting.

7.4 Educational Factors

• Teaching methods (GTM, CLT, TBLT, etc.).
• Quality of materials and input.
• Feedback and correction techniques.
• Assessment practices.

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8. Implications of SLA for ELT

• Provide rich, comprehensible input (i+1).
• Create low anxiety, motivating classrooms.
• Use pair work, group work, real communication (CLT, TBLT).
• Accept errors as part of learning, use them diagnostically.
• Encourage meaningful interaction, not just drills.
• Recognise individual differences among learners.

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9. Summary Table – SLA at a Glance

Aspect	Key Idea
Definition	Process of learning a language after L1
Important Theorists	Chomsky, Krashen, Long, Vygotsky
Core Concepts	Acquisition vs learning, input, interlanguage, errors
Stages	Silent → Early → Emergence → Intermediate → Advanced
Main Factors	Age, motivation, L1 influence, exposure, method

Second Language Acquisition helps teachers and researchers understand how learners actually develop language, so that teaching can be more effective, humane and scientifically informed.

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