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Linguistic competence and linguistic performance
Competence is what a speaker knows about their language. Performance is what they actually say, or understand, on a particular occasion.
The distinction
Noam Chomsky (1965) separated the two so that linguists could study the underlying system of grammar without being distracted by the messiness of everyday talk.
- Competence: the tacit knowledge of an idealised speaker–listener. It lets you produce and understand an unlimited number of sentences and decide whether a sentence is acceptable.
- Performance: actual language use, shaped by memory, attention, tiredness, nerves, noise and the situation.
Why the gap exists
People regularly say things that do not reflect what they know. Examples include false starts, hesitations, repetitions and slips of the tongue, such as saying heft lemisphere for left hemisphere. Conversely, you can judge sentences you would never produce. The rat the cat the dog chased bit ate the cheese is grammatical but very hard to process, because of limits on working memory, not because the grammar is missing.
| Competence | Performance | |
|---|---|---|
| What it is | Knowledge of the language system | Using that knowledge in real time |
| How we see it | Judgements of what is acceptable; patterns across many situations | Recordings and samples of actual speech and comprehension |
| What affects it | Learning and development | Memory, attention, fatigue, anxiety, task and setting |
Criticisms
- Communicative competence. Dell Hymes (1972) argued that knowing a language also means knowing when, where and how to use it appropriately, not only knowing its grammar.
- Variation is systematic. William Labov (1972) showed that variation in real speech follows patterns and is worth studying in its own right.
- No sharp line. Usage-based approaches (Bybee, 2006; Tomasello, 2003) argue that knowledge of language is built from experience of use, so competence and performance cannot be cleanly separated.
Why it matters in speech and language therapy
- Test scores are performance. A low score may reflect attention, anxiety, fatigue or an unfamiliar task rather than a gap in knowledge, so results are best compared across tasks and settings.
- Different tasks, different views. A language sample shows what someone does spontaneously (see type-token ratio), while a judgement task shows what they know.
- Multilingual speakers. Performance in a weaker language often underestimates what a person understands overall.
- Dialect is not incompetence. Speaking Singapore English or another variety is a competence in that variety (see Allophones 101).
Rule of thumb. Treat every observation as performance, and ask what competence it best supports. Repeat it under different conditions before drawing firm conclusions.
Sources and further reading
- Chomsky, N. (1965). Aspects of the Theory of Syntax. MIT Press.
- Hymes, D. (1972). On communicative competence. In J. B. Pride & J. Holmes (Eds.), Sociolinguistics. Penguin.
- Labov, W. (1972). Sociolinguistic Patterns. University of Pennsylvania Press.
- Bybee, J. (2006). From usage to grammar: The mind’s response to repetition. Language, 82(4), 711–733.
- Tomasello, M. (2003). Constructing a Language. Harvard University Press.