This thesis presents the results from three interrelated studies. The first study investigated the potential impact of different vocabulary learning strategies (VLS) as well as different learner styles on vocabulary size in Saudi Arabic-speaking students in higher education. Participants completed a VLS questionnaire and a vocabulary size test. The results implied that undergraduates tended to use simpler strategies than postgraduates. The strategies of guessing a word’s meaning from context and watching television related positively to lexical knowledge in both groups. Moreover, clustering analysis revealed two learner groups that varied in how frequently they used VLS overall, rather than in terms of which VLS they preferred. Those students who used more VLS overall also had greater vocabulary sizes, irrespective of educational level. Hence, the study found no evidence for differences in individual learner styles in the current groups. Consequently, it recommended that VLS usage should be encouraged overall, but that the need for teachers to cater to individual vocabulary learning styles may not be warranted.
The second study compared how lexical inferencing and lexical translation influence L2 vocabulary acquisition. Sixty-one undergraduate Saudi EFL students read target words in authentic reading materials and were either asked to guess their meaning or look it up in a dictionary. Pre- and post-tests were measured participants’ knowledge of target words and overall vocabulary size. The results show a significant and comparable learning effect for both vocabulary learning strategies, with a higher pre-test vocabulary knowledge related to a larger learning effect. Furthermore, the better participants were at guessing correctly, the better they learned vocabulary through inferencing. The results suggest that both VLS are equivalently effective and that learners’ overall vocabulary size influences the amount of learning that occurs when using these VLS. The third study used the same methods and participants as the second study to explore how vocabulary learning strategy usage and skills in the four language domains relate to participants’ increase in lexical knowledge and to the learning of specific vocabulary items over a certain period of time. Results showed that learning through inferencing, but not learning through dictionary use, depended on learners’ familiarity with the particular learning strategy. Additionally, the study revealed a complex relationship between reading comprehension, note taking, vocabulary size and attainment. The results suggest that familiarity with inferencing strategies may be beneficial for learners and that the relationship between note taking and vocabulary acquisition warrants further investigation.