Interlanguage: Definition, Formation & Effects

Lesson Transcript
Instructor: Ralica Rangelova

Rali has taught Public Speaking to college students and English as a Second Language; She has a master's degree in communication.

This lesson describes the four characteristics of interlanguage and the five factors in the interlanguage process, along with an example for each factor. It explains the process of fossilization and the importance of interlanguage to L2 teachers.


Imagine you are standing on a ledge. There's a huge gap, but you want to get to the other side. You can't jump across. You can't walk around. You can't fly over. But, you can build a bridge plank by plank. At first, you might be able to walk across carefully, but as you add to it, one day it might be strong enough to drive a car across! Now imagine your ledge is your native language and you are trying to conquer a second language: the other ledge. In this scenario, your bridge will be called interlanguage.

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  • 0:03 Interlanguage
  • 0:37 Definition
  • 1:31 Characteristics
  • 2:53 Interlanguage Formation
  • 5:09 Effects of Interlanguage
  • 6:32 Lesson Summary
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Interlanguage (IL) is a linguistic system used by second language learners. Learners create this language when they attempt to communicate in the target language. Interlanguage is affected by the learner's native language as they use their native language knowledge to understand and organize the second language or to compensate for existing competency gaps.

Nonetheless, interlanguage is entirely different from both the learner's first language (L1) and the targeted second language (L2). Interlanguage has its own rule system but it contains ungrammatical sentences and elements. Given that IL consists of elements of L1 and L2 as well as the speaker's perceptions, it is always unique from speaker to speaker. Learners create rules, and they are changed through input such as teachers, peers, etc. and by the learner.


Interlanguage is dynamic and permeable. It serves as a bridge between L1 and L2 when learners lack knowledge and fine mastery of rules, but over time, learners progress. They refine certain rules and obtain new ones. Their competence changes and their interlanguage starts to reflect those changes. First they may say: ''I no swimming,'' which later becomes: ''I don't swimming,'' until it reaches perfection: ''I don't swim.'' The process of constant extension and revision of rules reflects IL's tendency to change. IL's rules are not fixed: they're altered, deleted, or added.

Interlanguage is systematic. Although different learners have different interlanguage, they all have their own rules within their variations. They may not align with the actual rules but they are systematic: ''I received money, I buyed a new car, and I selled it.'' Rules are set in predictable ways.

Interlanguage is variable. Learner's performance is variable. They may apply the same rule differently in separate contexts or domains. Accuracy and fluency vary across occasions as learners have alternative rules for the same function. In a classroom setting, where the learner is focused on producing grammatically correct sentences, they may say: ''I don't drink coffee.'' In a spontaneous conversation, the same meaning can be expressed as: ''I no drink coffee.''

Interlanguage Formation

What affects the formation of interlanguage has been a topic of controversy and debate for decades. Currently, there five agreed-upon factors that are believed to shape how learners' create interlanguage: overgeneralization, learning strategies, language transfer, transfer of training, and communication strategies.


Overgeneralization involves learners extending the application of a rule in L2. They group similar items together and try to predict their behavior based on a rule they already know. Using the same rule in new situations leads to errors: the plural for ''deer'' becomes ''deers''; the past tense of ''go'' becomes ''goed.''

Learning Strategies of L2

Learning strategies consist of learners adopting different learning approaches. Some incorrect learning strategies may result in stagnation in the development of some aspect of L2, such as syntactic, lexical, or sociocultural. One such example is the act of simplification, as in ''I am clean my room now'' instead of ''I am cleaning my room now.''

Language Transfer

Language transfer involves learners using their knowledge of L1 to understand or produce meaning in L2. If L1 and L2 are very different, errors are likely to occur in L2, like ''I cats love.''

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