汉字识别中字形畸变和语境的ERP效应

ERP Effects of Twirled Chinese Characters and Semantic Priming in Character Recognition

以事件相关电位技术和语义启动范式,采用同一字判断(靶字延迟反应)作业,考察字形畸变和语境对低频汉字识别的影响。结果发现,无语义启动时,畸变靶字正确率低于清晰靶字;启动效应只体现在畸变时的正确率上。150–300ms窗口,畸变字比清晰字诱发峰值更负的N170;300–500ms时间窗口,不启动条件诱发平均波幅更负的N400,畸变字诱发更大N400。结论是,畸变字诱发的N170成分,在一定程度上反映了字形加工;N400的语义启动效应和畸变效应,扩展了Holcomb的研究,并支持语义提取理论。

The mental representation and processing of Chinese words are important topics in cognitive psychology. Using the ERP technique and a priming paradigm, the present study adopted a delayed character - matching task to investigate the character - twirling effects of Chinese characters of low frequency, and their interactions with semantic priming. Three characters were presented in succes- sion in each trial of a character - matching task, representing prime, target and probe stimulus respectively. The primes were intact characters, while both the targets and probes were twirled ones. Two variables, priming and twirling, were manipulated with a 2 x 2 factorial within - subjects design in the experiment, and ended up with four treatment conditions, which were primed twirled, primed in- tact, unprimed twirled, and unprimed intact conditions. The subjects were asked to press a key on keyboard if the target and the probe, which followed the target, were the same character in identity, and press another one if not. Sixteen native Chinese undergraduate or graduate students participated in the experiment during which they were instructed to make a yes/no distinction in the task. The behavioral data showed significant interactions between priming and twirled conditions. When the primes and targets were related, twirled targets were even responded to faster than were the intact. Moreover, the usual priming effect and twirled effect on accuracy were obtained, and there was significant interaction. The three- way repeated- measures of ANOVAs with factors of twirling （twirled, intact） , priming （primed, uuprimed）, and electrode site revealed significant main effects of twirling at the 150 - 300ms interval. The peaks of N170 elicited by the twirled targets were more negative compared to the intact targets. These findings support the notion that N170 reflects a perceptual analysis of visual character configuration. At the 300 - 500ms interval, similar ANOVAs but conducted on mean amplitude revealed significant main effects of both semantic priming and twirling, and revealed no significant interactions. The amplitude of N400 elicited by target charac- ters was significantly larger in unprimed conditions than in primed trials. More importantly, the amplitude of N400 was significantly larger in twirled than in intact conditions. This N400 - like （ stimulus - ） degradation effect provides an extension to Holcomb （ 1993 ）, who did not find such effect with English words of similar frequency. This N400 - like degradation effect is interpreted in terms of Kutaset al.＇s （2006） N400 notion of semantic retrieval, but it does not support the post - lexical processing theories. The difference in the style of meaning retrieval between Chinese characters and English words was discussed.