Holcomb P J
Department of Psychology, Tufts University, Medford, MA 02155.
Psychophysiology. 1993 Jan;30(1):47-61. doi: 10.1111/j.1469-8986.1993.tb03204.x.
Two experiments explored the effects of stimulus degradation on behavioral and event-related potential (ERP) measures of semantic priming. The primary goal was to help elucidate the psychological processes that underlie the N400 component. In both experiments, subjects made speeded lexical decisions to words and pseudowords preceded by either semantically related or unrelated prime words. In one block of trials, the target stimuli were intact, and in a second block they were degraded by removing a random 33% of the elements making up each letter of the target (Experiment 1) or by overlaying a matrix of dots on the target (Experiment 2). In both experiments, subjects responded faster and more accurately to related targets than to unrelated targets (behavioral semantic priming effect), and this priming effect was greater when the target was degraded. However, although the N400 component was larger for unrelated than related targets (ERP semantic priming effect), there was no evidence that this difference was larger in the degraded block of either experiment. These results indicate that the behavioral and ERP measures reported here appear to be tapping into different components of the process(es) involved in semantic priming. The implication of the results for the linguistic processes underlying the N400 are discussed.
两项实验探究了刺激退化对语义启动的行为和事件相关电位（ERP）测量的影响。主要目标是帮助阐明N400成分背后的心理过程。在两项实验中，被试对由语义相关或不相关的启动词之前呈现的单词和伪词进行快速词汇判断。在一组试验中，目标刺激是完整的，而在另一组试验中，通过随机去除构成每个目标字母的33%的元素（实验1）或在目标上叠加点阵（实验2）使目标刺激退化。在两项实验中，被试对相关目标的反应比对不相关目标更快、更准确（行为语义启动效应），并且当目标退化时这种启动效应更大。然而，尽管不相关目标的N400成分比相关目标更大（ERP语义启动效应），但没有证据表明在任何一项实验的退化组中这种差异更大。这些结果表明，这里报告的行为和ERP测量似乎涉及语义启动过程的不同成分。讨论了这些结果对N400背后语言过程的意义。
