Competence and performance are two important concepts within the field of linguistics that refer to different aspects of language use.
Competence refers to the abstract knowledge that speakers of a language have about the rules and conventions that govern that language. It is the underlying knowledge that allows speakers to understand and produce language. Competence includes knowledge of grammar, vocabulary, syntax, phonology, and semantics, among other aspects of language. Competence is often described as the idealized language ability of a speaker, or what they "know" about a language.
Performance, on the other hand, refers to the actual use of language by speakers in real-world situations. It is the concrete manifestation of a speaker's language ability, and it can vary depending on a number of factors, such as the speaker's level of attention, their memory capacity, and their emotional state. Performance includes the mistakes, hesitations, and other errors that speakers make when using language, as well as their use of non-standard forms of language, such as slang or dialect.
To illustrate the difference between competence and performance, consider the following example. A native speaker of English has a high level of competence in English grammar, and knows that the correct form of the third person singular present tense of the verb "to be" is "is." However, if that same speaker is tired, distracted, or nervous, they may make a mistake and say "he be" instead of "he is." This mistake is an example of performance, as it reflects a temporary lapse in the speaker's ability to use language correctly.
Another example of the difference between competence and performance can be seen in the way that language changes over time. Competence is largely stable over time, as it reflects the abstract knowledge that speakers have about a language. Performance, however, can change over time as speakers adapt to new situations and contexts. For example, the use of text messaging and social media has led to the development of new forms of language use, such as abbreviations and emoticons, which are not typically part of the competence of a language.
Linguists study both competence and performance in order to gain a deeper understanding of language and how it is used. By analyzing the idealized language ability of speakers (competence), linguists can identify the underlying structures and patterns that are shared across languages and that help to explain how language is learned and processed by the brain. By studying actual instances of language use (performance), linguists can gain insights into how language is used in different contexts and how it varies across different speakers and communities.
In conclusion, competence and performance are two important concepts within the field of linguistics that refer to different aspects of language use. Competence refers to the abstract knowledge that speakers have about the rules and conventions that govern a language, while performance refers to the actual use of language by speakers in real-world situations. By studying both competence and performance, linguists can gain a deeper understanding of language and how it is used, as well as the ways in which it changes over time.