| Term | Definition |
| behaviourism | A theory concerning how we learn. B.F. Skinner popularised its application to languages with Verbal Behaviour. Children produce linguistic responses to stimuli; if these are reinforced by positive feedback and become conditioned / habitual. |
| cognitivism / nativism | By contrast, cognitivists such as Chomsky assert language acquisition proceeds from a language acquisition device wired into our brains; all humans have this universal grammar which allows us to infer patterns and generate novel sentences. |
| the contrastive analysis hypothesis | This emerged from behavourism and identified L1 as having the biggest negative influence on L2 acquisition; and by scientifically / empirically contrasting and comparing the two languages, errors could be predicted. |
| interlanguage | The 'separateness' of a second language learner's system – it falls between the system of the native language and the target language. The term comes from Selinker (1972), and has also been called an approximative system and idiosyncratic dialect. |
| intralingual errors | Errors that result as a consequence of the development of interlanguage – notably 'overgeneralization' of rules. This is a cognitivist view of the sources of error. |
| interlingual errors | Errors that result of transfer from the native tongue – L1 interference. The Contrastive Analysis Hypothesis accounts for all errors this way. |
| A pre-systematic error | An error made as a result of the learner not yet knowing the rule. |
| A systematic error | The learner knows, or half knows, the rule and is able to apply it more or less consistently. An error at this stage can be self-corrected if the learner is prompted. |
| A post-systematic error | 'A mistake'. The learner's interlanguage system is pretty much mastered. An error can be self-corrected without prompting. |
| A mistake | An error that results from a slip or a random guess – i.e. a performance error. The rule is known but not applied. Think of the kind of lapses native / proficient speakers make when speaking. |
| An error | A manifestation of the state of the learner's interlanguage – a notable deviation from the adult grammar of a native speaker reflecting the interlanguage competence of the learner. |
| A global error | An error that causes confusion to the listener / reader – the message or intended meaning is lost due to the 'severity' of the error. |
| A local error | An error that doesn't interfere with the intended meaning and is easily recognised. |
| fossilization | A metaphor describing the relatively permanent presence of errors in a learner – particularly otherwise competent learners. It's not generally irreversible, but for some reason, the learner does not see the value of / need to reverse it. |
| Cognitive feedback | Direct feedback from a listener concerned with facts, suppositions or beliefs. It can be positive, negative or neutral, and the feedback is typically conveyed linguistically. |
| Affective feedback | By contrast, this feedback expresses the attitude of the listener and is given through 'kinesic mechanisms' – gesture, voice, facial expressions. It can also be positive, negative or neutral. |