Developmental Patterns in the Interlanguage Research

Interlanguage, defined as a dynamic language system created by the second language learners, can be studied by observing how the language of the learner develops over time. It is argued that interlanguage develops in a regular, predictable way. The regularity of interlanguage development can be confirmed by studying the order or the sequence of the acquisition of a certain structure. The former is studied by choosing one of the grammatical structures (i.e. plural-s), followed by collecting interlanguage samples to determine how often a certain structure is used and finally ranking the structure according to accuracy criteria. The latter deals with the detailed investigation of a certain feature (i.e. interrogatives) to show the sequence of stages through which a learner passes in his/her attempt to arrive at the target language. By studying syntactic structures, such as negatives and interrogatives, the regularities of the acquisition stages are most evident. The regularities have been found across many languages, in particular, English and German. To demonstrate that German language develops in a regular fashion, Processability Theory was proposed stating that L2 learners can produce only those L2 structures which they can process at any given point in time emphasizing thus the fact that developmental stages cannot be skipped. Furthermore, developmental patters can also be studied by applying obligatory occasion, target-like or frequency analysis. Both obligatory occasion and target-like analysis compare the learner's and the target language, whereas frequency analysis lists various linguistic devices used by the learner to express a certain grammatical structure and then shows the frequency of using a certain linguistic device.