Second language acquisition

Target audience: intermediate learners.

Various theories have been advanced to explain how second languages are acquired. Each of these seeks to account for a relatively uncontroversial set of observations that constitute the empirical base of Second language acquisition (SLA).


These observations deal with five principal topics:

  1. The nature of knowledge of the second language
  2. The nature of [[ Interlanguage ]]
  3. Influence of the first language
  4. The effect of the linguistic environment
  5. The effect of instruction

Knowledge of the second language

Theories of SLA differ widely as to their theory of the nature of second language knowledge. For some, this knowledge is present in an innate, specialized faculty of symbolic rules and representations (i.e. [[ Universal Grammar]] of [[Generative linguistics]]). For others (e.g. [[Usage-based approaches to SLA]] and [[Skill acquisition theory ]]), knowledge of language is similar to other kinds of knowledge. All, however, have to contend with two core observations:


The core findings regarding [[ Interlanguage ]] are that it is both systematic and variable.

Since human language is systematic, interlanguage must be systematic as well. This systematicity has been found in that Learners’ output proceeds along predictable paths.

But interlanguage is variable as well, both across [[ Subsystems of language ]] (see: Second language learning is uneven across subsystems of language) and between learners (see: Second language learning outcomes vary).

Influence of the first language

The idea that a learner’s first language has a major effect on second language acquisition played a large role in early theory, but much recent work has shown that, in fact, The effect of a second language learner’s first language is limited. Theories still differ about the magnitude and nature of the effect of the first language.

The linguistic environment

All theories agree that the linguistic environment plays an important role in second language acquisition, but the nature of this role, and the relative contribution of different aspects of the environment are matters of controversy. We know that Second language acquisition requires exposure to input but the that The effect of input frequency in SLA is limited. Furthermore, it also appears that The effect of learner output on second language acquisition is limited.


The role of instruction in second language acquisition is one of the most controversial topics in the field. Overall, it can be said that The effect of instruction on second language acquisition is limited, although the nature of these limits is still a topic of debate.


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