Vocabulary knowledge is central to a speaker's command of their language. In previous research, greater vocabulary knowledge has been associated with advantages in language processing. In this study, we examined the relationship between individual differences in vocabulary and language processing performance more closely by (i) using a battery of vocabulary tests instead of just one test, and (ii) testing not only university students (Experiment 1) but young adults from a broader range of educational backgrounds (Experiment 2). Five vocabulary tests were developed, including multiple-choice and open antonym and synonym tests and a definition test, and administered together with two established measures of vocabulary. Language processing performance was measured using a lexical decision task. In Experiment 1, vocabulary and word frequency were found to predict word recognition speed while we did not observe an interaction between the effects. In Experiment 2, word recognition performance was predicted by word frequency and the interaction between word frequency and vocabulary, with high-vocabulary individuals showing smaller frequency effects. While overall the individual vocabulary tests were correlated and showed similar relationships with language processing as compared to a composite measure of all tests, they appeared to share less variance in Experiment 2 than in Experiment 1. Implications of our findings concerning the assessment of vocabulary size in individual differences studies and the investigation of individuals from more varied backgrounds are discussed
Bibliographical noteAuthor Contributions
Substantial contributions to the conception or design of the work: NM, ZS, MB, and AM. Acquisition of data: NM. Analysis and/or interpretation of data: NM, ZS, MB, and AM. Drafting the work: NM. Revising it critically for important intellectual content: NM, ZS, MB, and AM. Final approval of the version to be published: NM, ZS, MB, and AM. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved: NM, ZS, MB, and AM.
We would like to thank Esther Janse for support with the PCA and the vocational colleges ROC Nijmegen, ROC Midden-Nederland, and ROC Tilburg for their cooperation and the possibility to conduct our experiment there.
This research was supported by the Max Planck Society for the Advancement of Science, Munich, Germany.