Temporal dynamics of form and meaning in morphologically complex word processing: An ERP study on Korean inflected verbs

The word stem is distinguished as the core component in verb inflections that envelopes essential semantic and syntactic properties, playing a central role in word processing. In the present study, in order to find the role of form and meaning during the visual recognition of morphologically complex words, the effect of the stem length of inflected Korean verbs was examined in an event-related potential (ERP) lexical decision experiment. Additionally, a potential modulation of whole-word frequency in morphological effect was investigated in order to locate the temporal locus of sublexical (i.e., morphological) and lexico-semantic processing. Behavioral results showed that lexical decision times were faster for targets with shorter stem length compared to targets with identical word length but longer stem length. A significant interaction between the whole-word frequency and stem length was also found, in which stem length effect was not significant in words with high frequency. The ERP data revealed corollary results; the frequency effect emerged as early as N100, followed by significant modulations of N250, N400, and P600 components. The stem length effect was demonstrated in latency ranges N250, N400, and N400. In the N400 component, the interaction of two factors was revealed in which stem length effect shown only in the medium- and low-word frequency levels, but not in the high-frequency level. Taken together, the present data provide evidence for simultaneous activation of morphological and lexico-semantic information in early visual word processing after scanning the whole-form of a word. The results are discussed in terms of the current models of morphologically complex word processing.