Effects of task type on morphosyntactic complexity across proficiency: Evidence from a large learner corpus of A1 to C2 writings

This study investigates the effect of instructional design on (morpho)syntacticccomplexity in second language (L2) writing development. We operationalised instructional design in terms of task type and empirically based the investigation on a large subcorpus (669,876 writings by 119,960 learners from 128 tasks at all Common European Framework of Reference for Languages levels) of the EF-Cambridge Open Language Database (EFCAMDAT; Geertzen, Alexopoulou and Korhonen 2014).

First, the 128 task prompts were manually categorised for task type (e.g. argumentation, description). Next, developmental trajectories of syntactic complexity from A1 to C2 were established using a variety of global (e.g. mean length of clause) and specific (e.g. non-third person singular present tense verbs) measures extracted using natural language processing techniques. The effects of task type were analysed using the categorisation from the first step. Finally, tasks that showed atypical behaviour for a measure given their task type were explored qualitatively.

Our results partially confirm earlier experimental and corpus-based studies (e.g. subordination associated with argumentative tasks). Going beyond, our large-scale data-driven analysis made it possible to identify specific measures that were naturally prompted by instructional design (e.g. narrations eliciting wh-phrases). We discuss which measures typically align with certain task types and highlight how instructional design relates to L2 developmental trajectories over time.