Derivational complexity vs. transfer effects

We investigate whether non-target wh-questions in heritage Low German and L2 English speakers are due primarily to cross-linguistic transfer or the reduction of grammatical complexity in developing grammars as modelled by the Derivational Complexity Hypothesis (DCH, Jakubowicz 2005). Previous research shows that complex (i.e. cross-clausal) wh-dependencies pose more difficulty to child L1 and adult L2 learners than monoclausal dependencies (Jakubowicz & Strik, 2008; Schulz, 2011; Slavkov, 2015). To avoid complex dependencies, learners often use medial constructions where the wh-item surfaces once at the left periphery of the embedded CP and a second time at the left periphery of the matrix clause. Medial-wh is ungrammatical in English, though possible in German and its varieties, e.g. the low German Plautdietsch. In this study, we investigate the linguistic behavior of twelve (n = 12) bilingual Plautdietsch-English speakers in Southwestern Kansas, analyzing their production and judgments of wh-questions in both languages. In production and judgment tasks, we find that, in the L1, only heritage speakers produced medial-wh, while in L2 English, only late L2 learners produced medial-wh. This pattern cannot be due to transfer, since speakers produce medial-wh in only one of their languages. Instead, medial-wh surfaces as a mechanism to reduce syntactic complexity in the less dominant language, irrespective of whether it is the L1 or the L2 or whether it was acquired early or late. We argue that the DCH can account for grammatical restructuring in both heritage L1 speakers and late L2 speakers and discuss its potential as a metric of incomplete acquisition and attrition in bilingual syntax.