Interlanguage

An interlanguage is an emerging linguistic system that has been developed by a learner of a second language (or L2) who has not become fully proficient yet but is only approximating the target language: preserving some features of their first language (or L1) in speaking or writing the target language and creating innovations. An interlanguage is idiosyncratically based on the learners' experiences with the L2. It can fossilize in any of its developmental stages. The interlanguage consists of: L1 transfer, transfer of training, strategies of L2 learning (e.g.simplification), strategies of L2 communication (e.g. do not think about grammar while talking), and overgeneralization of the target language patterns.

Interlanguage is based on the theory that there is a "psychological structure latent in the brain" which is activated when one attempts to learn a second language. Larry Selinker proposed the theory of interlanguage in 1972, noting that in a given situation the utterances produced by the learner are different from those native speakers would produce had they attempted to convey the same meaning. This comparison reveals a separate linguistic system. This system can be observed when studying the utterances of the learners who attempt to produce a target language norm.

To study the psychological processes involved one should compare the interlanguage of the learner with two things:

Utterances in the native language to convey the same message made by the learner
Utterances in the target language to convey the same message made by the native speaker of that language.
Interlanguage yields new linguistic variety, as features from a group of speakers' L1 community may be integrated into a dialect of the speaker's L2 community. Interlanguage is in itself the basis for diversification of linguistic forms through an outside linguistic influence. Dialects formed by interlanguage are the product of a need to communicate between speakers with varying linguistic ability, and with increased interaction with a more standard dialect, are often marginalized or eliminated in favor of a standard dialect. In this way, interlanguage may be thought of as a temporary tool in language or dialect acquisition.

http://en.wikipedia.org/wiki/Interlanguage