ABSTRACT
It is general consensus among researchers in second language acquisition (SLA) that the acquisition of a second language cannot be explained without taking a multitude of developmental conditions into account: individual factors (such as brain structures, working memory, intelligence, or motivation), social factors (parent–child interactions, family SES), and institutional factors (a specific school program, the intensity and duration of L2 contact, a submersive vs. immersive school context) have all been identified as influential for (S)LA in numerous studies. The exact contribution of these various potential influencing factors at work to predict and explain (S)LA remains an empirical question. This endeavor, however, is challenging. An appropriate explanation also requires the identification of causal and conceptual interrelations of variables. We outline conceptual problems with analyzing the predictive value of several factors at the same time, since these types of analyses are often not sufficient to confirm causal effects of factors on different hierarchical levels, since they remain “blind” to a number of theoretical problems. It is the goal of this contribution to discuss inherent difficulties connected to the investigation of influencing factors at different conceptual levels for developmental processes such as SLA.
