Lexical knowledge and L2 general language proficiency: collocational competence and vocabulary size as determinants of lexical knowledge.

This study investigates the contribution of receptive collocational competence and receptive vocabulary knowledge to L2 general language proficiency, and how well collocational knowledge develops in relation to knowledge of single-word items. To achieve this aim, measures tapping receptive collocation knowledge, receptive vocabulary knowledge and general language proficiency were administered to 86 Arabic-speaking learners of English at the university level. Results showed positive significant correlations of collocational competence (r = .78) and vocabulary knowledge (r = .70) with general language proficiency. Regression analysis revealed that collocational knowledge predicted the largest variance in general language proficiency, over and above, the prediction value of vocabulary knowledge. The results also showed that collocational knowledge develops as vocabulary knowledge increases, and that learners appear to first acquire collocations of items from more frequent word bands. Furthermore, the results indicated that knowledge of collocations and individual words within the third and fifth frequency levels predicted the largest variance in L2 general language proficiency. The findings of the study have important implications for the teaching and learning of L2 collocations and development of a learner's vocabulary knowledge, as these two variables appear to be determinant factors of L2 general language proficiency.