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The cognitive neuropsychological model of word processing
The model breaks single-word processing into components — auditory analysis, phonological input lexicon, semantic lexicon and conceptual system, phonological output lexicon and phonological output buffer — and each damaged component produces its own error pattern that can be located with tests such as PALPA.
Why it matters in the exam
This is one of the busiest topics in aphasia questions. Questions give test results — minimal-pair discrimination, auditory lexical decision, word-picture matching, oral and written naming — or examples of naming errors, and ask where the damage is. To answer, follow the route from input to output and ask which task is intact and which is impaired.
The distinguishing signs that recur: damage to the semantic lexicon affects both comprehension and production, in every channel, and abstract words are harder than concrete ones; damage to the phonological output lexicon affects oral naming only, the patient can define the word and rare words are harder; damage to the output buffer causes phonological paraphasias, depends on word length and also affects repetition of nonwords.
Key points
- Route: auditory analysis, input lexicon, semantic and conceptual, output lexicon, output buffer.
- Semantic: every channel impaired; abstract words are harder.
- Output lexicon: oral naming only; frequency effect; the patient can define the word.
- Output buffer: phonological paraphasias, length effect, impaired nonword repetition.
- Sorting pictures by category tests the conceptual system without words.
Summary table
| Damaged component | What is impaired | What is spared | Distinguishing sign |
|---|---|---|---|
| Auditory analysis | Minimal-pair discrimination, auditory comprehension and repetition | Written naming, reading | Everything that goes through hearing is impaired |
| Phonological input lexicon | Auditory lexical decision (is it a word) and spoken word comprehension | Minimal-pair discrimination | Normal discrimination with impaired lexical decision |
| Semantic lexicon | Comprehension and production in every channel; semantic paraphasias | The conceptual system (sorting pictures by category) | Oral and written naming equally impaired; imageability effect |
| Conceptual system | Non-verbal world knowledge, for example links between pictures | — | Failure even on non-verbal tasks such as Pyramids and Palm Trees |
| Phonological output lexicon | Oral naming; tip of the tongue | Comprehension, definition, written naming | Word frequency effect |
| Phonological output buffer | Production: phonological paraphasias, also in repetition and reading aloud | Comprehension | Length effect; nonword repetition impaired |
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Sources
- Kay, Lesser & Coltheart, PALPA: Psycholinguistic Assessments of Language Processing in Aphasia, 1992 — The language processing model
- Whitworth, Webster & Howard, A Cognitive Neuropsychological Approach to Assessment and Intervention in Aphasia, 2nd edition (2014) — Spoken word comprehension and production
- Howard & Patterson, Pyramids and Palm Trees Test, 1992 — Access to semantics from pictures and words
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.