The effect of frequency on learners’ ability to recall the forms of deliberately learned L2 multiword expressions

In incidental learning, vocabulary items with high or relatively high objective frequency in input are comparatively likely to be acquired. However, many single words and most multiword expressions (MWEs) occur infrequently in authentic input. It has therefore been argued that learners of school age or older can benefit from episodes of instructed or self-managed deliberate (or intentional) L2 vocabulary learning, especially when L2 is learned in an EFL environment and most especially when productive knowledge is the goal. A relevant question is whether the objective frequency of vocabulary items is an important factor in production-oriented deliberate L2 vocabulary learning. We report three small-scale interim meta-analyses addressing this question with regard to two-word English Adj-Noun and Noun-Noun expressions. The data derive from 8 original studies involving 406 learners and 139 different MWEs. Our results suggest that objective frequency has a weak, possibly negative effect in the deliberate learning of MWE forms.