Language Acquisition Stages

Why This Matters

Language acquisition is one of the most remarkable feats of human cognition—children master complex grammatical systems without explicit instruction, following a predictable developmental trajectory across cultures. This topic sits at the intersection of several core cognitive science themes you'll be tested on: nativist vs. empiricist debates, critical periods, statistical learning, and the relationship between thought and language. Understanding these stages helps you grasp how the mind bootstraps itself into linguistic competence and why language serves as a window into cognitive architecture.

Don't just memorize the age ranges for each stage—know what cognitive capacities each stage reveals and what theoretical debates the evidence supports. When you see an exam question about language development, you're really being asked about underlying mechanisms: Is the child demonstrating innate grammatical knowledge? Statistical pattern recognition? Social learning? Each stage provides evidence for different theoretical positions, and that's where the points are.

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Pre-Speech Foundations

Before producing recognizable words, infants are already building the cognitive and perceptual infrastructure for language. These stages demonstrate that language acquisition begins with pattern recognition and social engagement, not speech production.

Prelinguistic Stage

• Birth to 12 months—infants communicate through crying, cooing, and gestures while building foundational skills for later language
• Perceptual narrowing occurs as infants tune into their native language's phonemes, losing the ability to distinguish non-native contrasts by around 10 months
• Joint attention and turn-taking behaviors emerge, establishing the social scaffolding critical for language learning

Babbling Stage

• 4-6 months onset—infants produce repetitive consonant-vowel combinations like "ba-ba" and "da-da," practicing the motor patterns of speech
• Canonical babbling is universal across languages and even occurs in deaf infants exposed to sign language, suggesting an innate drive to produce language-like sequences
• Phonetic drift gradually shapes babbling toward native language sounds, demonstrating early statistical learning from environmental input

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Early Word Use

The transition to meaningful speech reveals how children map sounds to concepts and begin using language symbolically. These stages highlight the tension between limited production capacity and sophisticated underlying comprehension.

One-Word Stage (Holophrastic Stage)

• 12-18 months—single words function as entire sentences, with "milk" potentially meaning "I want milk" or "there's milk" depending on context
• Holophrases demonstrate that children understand communicative intent before they can produce complex syntax
• Fast mapping allows children to learn new words after minimal exposure, suggesting specialized word-learning mechanisms

Two-Word Stage (Telegraphic Speech)

• 18-24 months—children combine words into minimal sentences like "want cookie" or "daddy go," omitting grammatical function words
• Word order follows consistent patterns (agent-action, action-object), revealing emerging knowledge of syntactic structure
• Semantic relations expressed include possession, location, and recurrence—the child encodes meaning systematically despite limited output

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Grammatical Expansion

As vocabulary grows, children begin acquiring the morphological and syntactic rules that give language its generative power. These stages provide critical evidence for rule-learning versus item-based learning debates.

Early Multiword Stage

• 24-30 months—sentences expand to three or more words with a vocabulary explosion (often 50+ new words per week)
• Overregularization errors like "goed" and "mouses" demonstrate that children extract grammatical rules rather than simply imitating adult speech
• Mean Length of Utterance (MLU) becomes a key measure of linguistic development during this period

Later Multiword Stage

• 30 months to 5 years—children master complex structures including embedded clauses, conjunctions, and prepositions
• Grammatical morphemes are acquired in a predictable order (present progressive → plural → past tense), supporting theories of maturational constraints
• Pragmatic skills develop alongside grammar—children learn to adjust speech for different listeners and contexts

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Mature Competence

The final stage represents the achievement of adult-like linguistic ability, though language learning continues throughout life. This stage raises questions about what changes after the critical period closes.

Adult-Like Language Stage

• By age 5-6—children demonstrate mastery of core grammar, with vocabulary and pragmatic refinement continuing into adolescence
• Metalinguistic awareness emerges, allowing children to think about language itself—making jokes, detecting ambiguity, and learning to read
• Critical period hypothesis suggests that this native-like acquisition becomes increasingly difficult after puberty, with second-language learners showing different neural patterns

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Quick Reference Table

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Self-Check Questions

1. Which two stages provide the strongest evidence that children extract grammatical rules rather than simply memorizing adult utterances? What specific phenomena support this?

2. Compare the prelinguistic and babbling stages: both precede meaningful speech, but what different aspects of language readiness does each demonstrate?

3. A child says "my feets are cold." What stage does this represent, and why is this error actually evidence of sophisticated cognitive processing?

4. How does the transition from holophrastic to telegraphic speech inform the debate between nativist and empiricist theories of language acquisition?

5. If an FRQ asks you to evaluate the critical period hypothesis, which stages and what types of evidence would you draw on to construct your argument?