Brain Dynamics Reflects Phonological And Semantic Top-Down Influences During Orthographic Processing Of Novel Word Forms

Abstract

The acquisition of new vocabulary is usually mediated by previous experience with language. In visual domain, orthographically unfamiliar word-forms may already have corresponding phonological or even conceptual representations in linguistic system, which facilitates orthographic learning. The neural correlates of this advantage were investigated by recording EEG during reading novel and familiar words across three different experiments (n=22 each), manipulating the availability of previous knowledge for the novel written words. In Experiment 1, participants received no previous training before reading these stimuli; Experiments 2 and 3, however, provided a previous training (six exposures) in the phonology of novel words (auditory exposure) and in both phonology and meaning (auditory exposure + picture), respectively. During reading, a different pattern of ERP responses was found for the novel written words depending on their previous training, resembling cross-level top-down interactive effects during the process of vocabulary acquisition. Thus, whereas phonological experience produced a different modulation at early lexical (~180 ms) and post lexical (~520 ms) stages of visual recognition of novel written words, additional semantic training influenced their lexical processing at a later stage (~320 ms). Importantly, a clear lexicality effect was found at the early peak in experiment 1 (no previous training); however, neural responses for trained and familiar words were found indistinguishable at this latency regardless of the phonological or semantic nature of training, reflecting similar orthographic processing and word-form access. These results suggest the key role of phonology in orthographically transparent reading systems, in which bidirectional decoding mechanisms contribute to the rapid formation of novel word-form representations even in the absence of visual exposure.