Skinner tried to analyse language behaviour under the term involving 3 external factors: frequency, imitation and reinforcement.

According to Chomsky, children are born with .

The most outstanding concept of Vygotsky's Sociocultural Theory is the , which relates to the difference between what an individual can achieve independently and what they can achieve through guidance and scaffolding

Environmentalist theories suggest that the individual’s environment shapes both and , that is, that the individual’s experience is of more significance to development than its .

• Enclosure: when cultures share social , enclosure is low, supporting language learning.

• : strong contact within the native culture with few contacts outside the community increases the social distance.

Nativist theories hold that language acquisition is an innate . Thus, human abilities and are encoded at birth, and language acquisition occurs as a natural part of human .

Interactionist theories rely both on and factors. According to these theories, children learn language out of a desire to with the world around them. Hence, language emerges from .

The Interaction Hypothesis is a theory proposing that one of the most effective methods in second language learning is by means of and .

Vygotsky believed that learning is an and process, where language is developed from social interactions. According to this theory, second language learners advance to higher levels when they interact with more knowledgeable speakers, such as a . Thus, the plays a crucial role in language acquisition.

Negotiation of meaning can be thus defined as the process by which addresser and addressee the and linguistic , grammatical structures or message until they reach mutual understanding.

Negotiation of meaning involves several communicative strategies:
• , which consists of attributing to the target language all features of their first-language translation equivalent.
• and , which consist of avoiding structures which are found to be difficult, and using forms which are known rather than trying out new structures, respectively.
• , which consists of repeating the utterance using different words or expressions.
• , which consists of applying a rule or pattern in a situation in which it does not apply in the target language.
• , which consists of reduction of the language due to inability or insecurity of learners.

The awareness of errors is important to teachers and learners, since it enables them to check their and enhance their . Hence, studying errors serve two main purposes: they provide , and they indicate which parts of the curriculum are the most difficult for students.