Proceedings of the Annual Meeting of the Cognitive Science Society

We investigate the accuracy development of the Englisharticle by learners of English as a second language. The studyfocuses on individual learners, tracking their learningtrajectories through their writings in the EF-Cambridge OpenLanguage Database (EFCAMDAT), an open access learnercorpus. We draw from 17,859 writings by 1,280 learners andask whether article accuracy in individual learners fluctuatesrandomly or whether learners can be clustered according totheir developmental trajectories. In particular, we apply k-means clustering to automatically cluster in a bottom upfashion learners with similar learning curves. We followlearners for a period covering one CEFR level. Given therelatively short learning window, the majority of learnersfollow a horizontal line. Nevertheless, we also identify groupsof learners showing a power-function and U-shaped curve.Crucially, these groups are ‘hidden’ when the aggregate oflearners is considered, a finding highlighting the importanceof individual level analysis.