RESEARCH ARTICLE Learning Word Meanings: Overnight Integration and Study Modality Effects

According to the complementary learning systems (CLS) account of word learning, novel words are rapidly acquired (learning system 1), but slowly integrated into the mental lexi-con (learning system 2). This two-step learning process has been shown to apply to novel word forms. In this study, we investigated whether novel wordmeanings are also gradual-ly integrated after acquisition by measuring the extent to which newly learned words were able to prime semantically related words at two different time points. In addition, we inves-tigated whether modality at study modulates this integration process. Sixty-four adult par-ticipants studied novel words together with written or spoken definitions. These words did not prime semantically related words directly following study, but did so after a 24-hour delay. This significant increase in the magnitude of the priming effect suggests that se-mantic integration occurs over time. Overall, words that were studied with a written defini-tion showed larger priming effects, suggesting greater integration for the written study modality. Although the process of integration, reflected as an increase in the priming effect over time, did not significantly differ between study modalities, words studied with a written definition showed the most prominent positive effect after a 24-hour delay. Our data sug-gest that semantic integration requires time, and that studying in written format benefits semantic integration more than studying in spoken format. These findings are discussed in light of the CLS theory of word learning