An Analysis of the Discourse Domain Hypothesis and Its Adequacy in Explaining Topic-Based Interlanguage Variation

This type of discourse is informed by the Discourse Domain Hypothesis (DDH) which arose from topic-based interlanguage (IL) variation focused by the learners of L2. This work appraises critically how DDH is formulated in a theoretically adequate manner by applying the applicable rules of theory construction in science and guidelines for the SLA. It is established that the DDH has been studied and written about extensively; however, our firm critique of these investigations reveals the serious challenges posed in the absence of definitional clarity of core concepts like ‘discourse domain’, the methodological barriers of operationalization, and the lack of the detailed specification of causal mechanisms. The journey of DDH can be traced across three significant concepts: it began with Selinker and Douglas, the integration of schema-theory proposed by Whyte to Douglas’s further sociocultural-based modification, which demonstrates both theoretical advancements and constant challenges. Even though all revisions made in this study were able to cover some of the previous caveats, the central concerns of construct validity, empirical test validity, and the ability of the model to explain a phenomenon still persist. The discussion points to the clear, postulated gaps in the current research which comes down to the need for further refinements on topic-based IL variation between SLA learners, better focused research directions, and no less potential inclusion of existing SLA models that are aimed at the same phenomena.