Acquisition of L2 (Second Language)

L2 acquisition, as well as L1 acquisition, happens through a non-conscious and natural process. The following video summarizes the main features and factors of SLA, and also some hypothesis about the subject:

Interlanguage is a concept introduced by Larry Selinker to define the intermediate stage of second language learners where they preserve some features of their first language, and can also overgeneralize some L2 speaking and writing rules. The result of this two characteristics is a unique linguistic system. This interlanguage gradually develops as the learner is exposed to the target language.

From this Interlanguage stage comes a phenomenon called Language Transfer, which happens when learners find similarities between two languages and apply the knowledge they have of one language on another one. Language transfer is not always from the learner’s native language; it can also be from a second language, or a third. Neither is it limited to any particular domain of language; language transfer can occur in grammar, pronunciation, vocabulary, discourse, and reading.

Stephen Krashen's Input Hypothesis set the differences between learning and acquisition, while it also claims that L2 acquisition process is just the same as L1 acquisition, since both adults and children can subconsciously acquire language, by comprehensible input. However, subsequent theories, such as the Comprehensible Output Hypothesis, by Merrill Swain, claim that only input itself it's not enough to develop a second language. L2 learners also need the opportunity to interact and produce their own speech, in order to encounter gaps in their linguistic knowledge and modify their output, learning something new as they do it.