儿童Stroop效应加工阶段特点的事件相关电位研究

选用小学六年级儿童为被试者,采用事件相关电位研究了Stroop效应的时间进程。实验中要求被试者判断在计算机屏幕中央出现的汉字颜色,并尽可能又快又准地按下相应的键,同时使用32导电极帽记录被试者的脑电信号。结果除了发现反应时的Stroop效应;还发现在汉字出现后大约300 ms左右,颜色与语义不一致的汉字诱发的P300比其它两种条件的波幅要大、潜伏期要晚;在汉字出现大约400 ms之后引发了一个慢波,不一致条件和控制条件引起的慢波波幅在头皮顶部比一致条件大。结果说明儿童Stroop效应的产生是一个复杂过程,干扰效应是早期颜色识别和后期反应选择两个阶段共同作用的结果,而促进效应则发生在后期的反应选择阶段。

An ERP Study on Processing Stages of Childrens Stroop Effect

The temporal course of the Stroop effect was investigated by event related potential(ERP) technique with . children of sixth grade. Subjects were asked to identify the display color of the Chinese characters by pressing the corresponding key as quickly and accurately as possible. The brain electric singnals were recorded by a 32-channel ERP/ EEG system. Besides the behavioural data, the evidence from the ERP data for the Stroop effects was also observed. It is resulted that the first ERP effect was obtained at about 300 ms post stimulus onset. The P300 amplitude induced by inconsistent condition is larger than that in consistent and neutral conditions, while the P300 latency for incongru-ent trials is the slowest. The second ERP effect generated by colored characters is a slow wave emerging at about 400 ms after the stimulus onset. There were significant trial type differences at posterior sites but not at frontal sites. Further comparisons showed that the mean amplitude for incongruent trials and controls was larger than congruent trials. These findings indicate that Stroop effect in children involves a complex process. The interference effect is the result of assembling the early stimuli evaluation stage and later response selection stage, while the facilitation effect may occur at the later stage for response selection.