Key research themes
1. How can vocabulary size be accurately measured and estimated across different populations?
This theme addresses the methodologies and challenges in assessing vocabulary size, focusing on test design, word counting units (word family vs. lemma), sampling procedures, and the influence of factors such as guessing and loanwords on test scores. Accurate measurement matters because vocabulary size estimates are essential for understanding language proficiency, tailoring instruction, and comparing populations such as native speakers, second language learners, and undergraduates.
2. What lexical and test design factors influence the difficulty and validity of vocabulary size test items?
This theme focuses on understanding which specific word properties and testing features impact learners' performance on vocabulary size tests. Factors include word frequency, length, concreteness, polysemy, morphological complexity, loanword status, as well as test format elements like inclusion of ‘I don’t know’ options and item sampling strategies. Insights in this area inform how tests can better discriminate true lexical knowledge from guessing and partial knowledge—thus improving validity and fairness.
3. How does vocabulary size relate to language proficiency and academic achievement, and how can vocabulary testing inform pedagogy?
This theme investigates the empirical links between measured vocabulary size and learners’ language skills such as reading comprehension and speaking ability, as well as academic performance. It also considers how vocabulary testing results can guide targeted vocabulary instruction and curriculum design, highlighting the nuances of receptive vs. productive vocabulary knowledge and the pedagogical implications for different learner populations and contexts.