The Comparative Fallacy in SLA Literature

Learners’ language has been described as transitional competence (Corder, 1967) and interlanguage (Selinker, 1972), and it has been categorized as a natural language (Adjemian, 1976). This indicates that learners possess their own languages. However, the question remains whether or not learners’ language has been explained and understood on its own, and not merely compared to target-language (TL) norms in the SLA literature (Cook, 1999). Bley-Vroman (1983) asserts that comparing learners’ language to TL norms may preclude researchers from an understanding of the systematic nature of a learner’s system, which in turn results in the comparative fallacy. He also warns that “[t]he comparative fallacy can have very serious effects on the validity of empirical studies in the way that it influences the interpretation and classification of data” (p. 15). In this paper, I will discuss two studies on the efficacy of corrective feedback on rule generation from the perspective of the comparative fallacy. Considering Bley-Vroman’s caution that, “any study which classifies interlanguage (IL) data according to a target language (TL) scheme or depends on the notion of obligatory context or binary choice will likely fail to illuminate the structure of the IL” (p.15), I will focus in particular on how the studies assess and analyze learners’ linguistic gains and interlanguage systems. First, I will briefly summarize two studies – Carroll & Swain (1993) and Tomasello & Herron (1988) – and then discuss the studies with regard to the comparative fallacy.