Early and automatic processing of written Chinese: visual mismatch negativity studies

Fluent reading entails multiple levels of analysis including orthography, syntax and semantics but is also characterised by fast speed and apparent ease in understanding the various linguistic input. This thesis therefore focuses on the earliness and automaticity of single word recognition, which is a fundamental component of reading process. Exactly when a visual stimulus is recognised as a word and comprehended, and to what extent this is an automatic and not a controlled process, are two of the most debated issues in psycholinguistic research. A series of six Event-Related Potential (ERP) studies were carried out in this study, with the first five of these investigating Chinese single character words and pseudowords and the sixth investigating Spanish words and word-like strings. The critical ERP component of interest is visual Mismatch Negativity (vMMN), a visual counterpart of the well-documented auditory MMN (Näätänen, Gaillard, & Mäntysalo, 1978). VMMN has recently been demonstrated to be a neural index of automatic processing of not only generic visual features but also written words. To overcome the compounding of physical differences between stimulus conditions, a “same-stimulus” identity oddball paradigm was adopted throughout the studies. The vMMN was computed by comparing the ERP responses to deviant and standard stimuli of the same lexical/semantic category. It was found that lexical and semantic vMMN effects could be obtained within the first 250 ms after the stimulus onset, even when the critical words were presented briefly and outside of the focus of attention (perifoveally) and participants were instructed to carry out a non-linguistic distraction task, indicating automaticity of processing. The similarity in the timing of these early vMMN responses lends support to parallel processing models of linguistic information processing. In addition, vMMN to changes in lexicality was subject to configurations in the cognitive system, with attention and the magnitude of deviance revealed as two important variables. Language vMMN effects in normal adults as revealed in this thesis may serve as a benchmark for assessing the reading abilities of first or second language readers, as well as of people with linguistic impairments, such as dyslexia