关键词: N400, 汉字, 正字法家族, ERPs

Abstract: There is a major concern highlighted in the literature that previous findings in alphabetical language studies regarding the N400 effect of neighborhood size may be confounded by phonological neighborhood size. A major purpose of this study is to resolve this concern. The stroke-based neighborhood size of a Chinese character is defined in this study as the number of characters that can be formed by replacing strokes of the root character. Event-related brain potentials (ERPs) elicited by target characters were recorded while participants completed a character-matching task where in a probe character was matched on each trial with its preceding target character. The task was performed to avoid potential P300 contaminations related to immediate responses and/or decisions to the stimuli. Using the delayed character-matching task, we manipulated the number of stroke-based neighbors of the target characters to study Chinese character orthographic neighborhood effects and to explore whether ERPs are influenced by cognitive processing during Chinese character recognition. In this study, characters of the highest frequency in their neighborhood were used as stimuli in order to eliminate the influence of the higher-frequency neighbors. The orthographic neighbors of Chinese characters were defined at stroke level. The neighbors of the characters were created by replacing 1 to 5 random strokes of the root characters depending on the total number of their strokes while keeping their structure and the orientations of their remaining strokes relatively constant. Actual neighbors of each target (selected) character determined by extra group of participants, who received a paper-pencil task in which they wrote the neighbors according to this definition and instructions provided. A total of 140 stimulus characters were then selected from the root characters to form 2 types of stimuli: characters with a large and characters with a small number of stroke-based neighbors which were each identified by at least 2 of the participants during the task. Character frequencies, stroke counts and radical counts were balanced across these types. The results revealed a greater N400-like deflection, a higher N250 and a lower P200 elicited by characters with a large number of neighbors compared with similar characters with a small number, while revealing no significant difference in behavioral performance across the neighborhood sizes. Given that the stroke-based neighborhood is free of a confounding phonological one, one implication of the present N400-like effect is that an N400 effect of neighborhood size can be generated without the confounding influence of the phonological neighborhood. Thus, the finding of the present N400-like effect can resolve the major concern highlighted in the literature, namely, that previous findings regarding the N400 effect of neighborhood size may be confounded by phonological neighborhood size. Furthermore, the N400-like effect of neighborhood size can be interpreted in terms of lateral inhibition within word level in the interactive activation model. The present P200-like effect of neighborhood size likewise suggests that P200 can be generated without the confounding influence of the phonological neighborhood or can be generated by orthographical processing alone. In conclusion, the present results are consistent with the interactive activation model and support the role of orthographical processing in generating both P200 and N400. The N400 may be better further interpreted as reflecting impeded retrieval of the character’s meaning.

Key words: N400, Chinese character, Orthographic neighborhood size, ERPs