Experimental And Theoretical Research On Chinese Character’s N400Fonts Effect

Language is an important function of the human brain, and it plays an irreplaceable role in people’s social interaction, individual cognition and personality development. N400is an ERPs component which is indexed as semantic processing of language cognition of the brain. So a great deal of psychological research on language was acquired through researches of the N400. In this paper, the cognitive meaningof N400is focus of our interest. N400effect reffers that the N400amplitude for one condition is smaller than another one. In repetition priming and semantic priming studies, N400amplitude for primed targets were smaller than unprimed targets and the phnomenon was so caller N400priming effects. The N400effects observed by related words, word and pictuer matching, or incongruent ending of sentences, were explained by Post-lexical Processing Theroy, which indexed the efforts at integrating the meaning of the stimulus in its context. The more difficult of the integrating the lager N400amplitude would be. Whereas the N400effects observed in lexical decision, or pseudo-words priming paradigm, were explained by Pre-lexical Processing or Lexical Processing Theory. Deacon (2004) prompted Lexical Processing to deny the ambiguous view of Pre-lexical Processing. He believed that N400indexed the analysis of orthographic and phonetic aspects of a word. Recently, Debruille (2007) summarized the previous researches and put forward that N400index semantic inhibition of the activated but inappropriate konwledge. The more it has to be inhibited, the larger the N400amplitude. So, it’s thus clear that the cognitive meaning of N400hasn’t been agreed according the current N400theroies.As were proved, N400effects were observed not only in pseudo-words paradigm, but also in studies using sentences and related words. So we believe it’s wrong to argue pure lexical or pure semantic processing when discuss N400cognition meaning. In this research, we operated Chinese character font as variable, to investigate both how the lexical and semantic aspects affect the N400. Experiment1, the veriable was character fonts (Song Ti vs Xing Kai Ti), the task was lexical decision (character vs pseudo-character). We assume that the font of Chinese characters directly determines the difficulty of retrieving conceptual knowledge of a character, which in turn determines the N400amplitude. N400indicated the retrieving difficulty from visual traits to character semantic.Experiment2investigated the N400font effect using low frequency characters, and using the same pseudo-characters used in Experiment1. It turned out that low frequency characters presented in Xing Kai Ti elicited larger N400amplitude than did the same characters in Song Ti. The interaction of character font and frequency was significant; This suggests that both font and frequency modulate N400, and that these N400effects reflect a sensitivity of the N400to orthographic retrieval processing. The N400font effects conform a lexical verification explanation of N400. The font and frequency both affect verification or matching process. Whenever the verification is more difficult, N400would get larger. These N400font effects apparently reflect relative difficulty in retrieving directly from orthography the meaning of Xing Kai Ti characters compared with Song Ti characters.Accroding to the two experiments, we drew conclusions as follow:First, using character fonts as the variable, we found a large N400elicited by stimuli (characters or pseudo-characters) presented in XKT font compared with ST font, indicating that N400’s sensitivity to orthographical processing of Chinese characters and a visual form-to-meaning process in recognizing Chinese characters. The finding of this study proved the lexical processing theory and agreed with the inhibition theory in a way, while it againsted the post-lexical processing theory which take the N400as simply sematic integration. We proposed here the verification theory for N400lexical effects, which means more matching circle numbers the more negative of N400amplitude, and it’s the same way with matching difficulty.Second, N400of Chinese characters was sensitive to fonts and other orthographical factors, and the amplitude of N400reflected a general index of the difficulty of retrieving sematic or conceptual knowledge from lexical representations.