Mainz, N. 1 , Shao, Z. 1 , Brysbaert, M. 2 & Meyer, A. S. . 1, 3
1 1. Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
2 2. Department of Experimental Psychology, Ghent University, Belgium
3 3. Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
The present study investigated the effects of individual differences in vocabulary size on language comprehension and production in adult native speakers.
Vocabulary knowledge of 67 Dutch speakers was assessed using five original and two established open and multiple-choice tests. We used various measures addressing receptive (multiple-choice tests) and productive (open tests) vocabulary to assess word knowledge reliably and comprehensively. Despite differences in test format, participants' scores on the different vocabulary measures were strongly correlated, and no clear distinction between receptive and productive vocabulary tests was found. For the individual differences analyses, factor scores were calculated representing each participant's performance across all vocabulary tests.
Language processing performance was measured using a lexical decision task, where we manipulated word frequency, and a picture-word interference (PWI) task including distractor frequency and relatedness manipulations. Mixed-effects model analyses showed significant word frequency and vocabulary effects in the lexical decision task, and significant effects of semantic interference, distractor frequency, and vocabulary in the PWI task. Thus, enhanced vocabulary size predicted faster language processing in both comprehension and production. The size of the frequency and distractor effects was not moderated by vocabulary, indicating that individuals with larger vocabularies retrieve words overall faster independent of lexical characteristics.