One key characteristic of these features is that they reflect variation across languages in their overtness, which became particularly important to GenSLA research. A feature of a word or phrase is said to be overt if there is surface evidence of its existence within that word or phrase. By contrast, a feature of a word or phrase is said to be covert if there is no surface evidence of its existence within that word or phrase. This made interesting predictions about adult L2 learning behaviour, for example, that L2 overt morphology should be easier to acquire if the learner has similar overt features in their L1. In one relevant study it was shown that Russian but not Japanese L2 learners of English were, in line with these predictions, reliably sensitive to English plural errors, (Russian has overt plural morphology while Japanese does not).Jiang, N., Novokshanova, E., Masuda, K., & Wang, X. (2011). Morphological congruency and the acquisition of L2 morphemes. Language Learning, 61, 940–967.
