Language
High-Yield Summary
- Language has five components: phonology (sound, phonemes), morphology (word structure, morphemes), semantics (meaning), syntax (sentence structure), pragmatics (context-dependence, shaped by prosody).
- Development timeline: babbling in year 1 → ~1 new word/month at 12-18 mo → vocabulary 'explosion' ~18 mo → word combinations at 18-20 mo → longer sentences with normal grammatical errors at 2-3 yrs → substantially mastered by 5.
- Three acquisition theories: Nativist (Chomsky's innate Language Acquisition Device, transformational grammar, a critical period ~age 2-puberty — illustrated by Genie), Learning/Behaviorist (Skinner's operant conditioning, doesn't explain the explosion), Social Interactionist (biological + social drive to communicate).
- Critical period = a hard, near-absolute window (Chomsky); sensitive period = a softer window of maximal but not exclusive effect.
- Whorfian/Linguistic Relativity Hypothesis: language shapes (not rigidly determines) how people think and perceive reality.
- Language circuitry sits on the dominant (usually left) hemisphere: Broca's area (production, inferior frontal gyrus) and Wernicke's area (comprehension, superior temporal gyrus), connected by the arcuate fasciculus. Damage produces distinct aphasias.
Key Terms
- Phoneme
- An individual speech sound; English has roughly 40.
- Morpheme
- The smallest unit of language that carries meaning (e.g. '-s' for plural).
- Language Acquisition Device (LAD)
- Chomsky's theoretical innate brain mechanism for absorbing the rules of language.
- Transformational grammar
- Changes in word order that preserve the same underlying meaning; central to Chomsky's Nativist theory.
- Arcuate fasciculus
- Axon bundle connecting Broca's and Wernicke's areas, linking comprehension and production.
Nativist vs. Learning (Behaviorist) Theory of Acquisition
| Nativist (Chomsky) | Learning / Behaviorist (Skinner) |
|---|---|
| Innate biological capacity for language (LAD); critical period ~age 2-puberty | Operant conditioning: caregivers reinforce sounds resembling real speech |
| Explains the sudden vocabulary explosion | Explains gradual word/speech development, but not the explosion |
Language Development Timeline
- 1First year: babbling begins spontaneously (even in deaf infants, who stop quickly since they can't hear themselves).
- 212-18 months: roughly one new word added per month.
- 3~18 months: vocabulary 'explosion' — rapid growth; gestures, inflection, and context are essential for understanding.
- 418-20 months: children begin combining words into short phrases.
- 52-3 years: longer sentences, rapidly expanding vocabulary, with normal grammatical errors.
- 6By 5 years: language is substantially mastered.
Critical Period vs. Sensitive Period
| Critical Period | Sensitive Period |
|---|---|
| A hard cutoff — after it closes, full mastery (e.g. syntax) may be permanently out of reach | A softer window of maximal effect — some learning is still possible after it ends |
| Evidenced by Genie: learned vocabulary but never mastered syntax | Applies more broadly to skills with graded, not absolute, sensitivity to timing |
Broca's vs. Wernicke's Aphasia
| Broca's (Expressive) Aphasia | Wernicke's (Receptive) Aphasia |
|---|---|
| Comprehension intact; production reduced, halting, effortful | Production fluent but nonsensical; comprehension lost |
| Damage near the inferior frontal gyrus | Patients often believe they're speaking/understanding fine; damage near the superior temporal gyrus |
Common MCAT Trap
- A passage testing one acquisition theory's predictions shouldn't be answered using another theory's logic — Nativist, Learning, and Social Interactionist are distinct, competing accounts.
- The Whorfian hypothesis claims language shapes thought, not that it rigidly determines what a person can think or perceive.
- Conduction aphasia is distinct from both Broca's and Wernicke's: production and comprehension are both intact, but repetition is impaired — a signature of arcuate fasciculus damage specifically.
- Critical period = hard cutoff; sensitive period = softer window of maximal effect — don't treat them as synonyms.
Quick Recall
A patient speaks fluently but produces nonsensical word combinations and doesn't realize anything is wrong. Which aphasia, and which brain area?
A patient can speak and understand normally but cannot repeat a sentence just said to them. What's damaged?
What did the case of Genie provide evidence for?
Which component of language governs how a person's speech style shifts depending on who they're talking to?
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