Kusak G, Grune K, Hagendorf H, Metz A M
Institut für Psychologie, Humboldt-Universität zu Berlin.
Z Exp Psychol. 1997;44(1):38-61.
In recent experiments with a pseudo-random sequence of 7 consonants to recall after trial (stimulus onset asynchrony 1000 ms) a reverse relationship between P300 amplitude of the event-related potential (ERP) and letter presentation position was shown (Grune et al., 1996). It was assumed that this relationship reflects competition between encoding and retention processes in this time regime. In order to find evidence for the resource competition hypothesis in working memory a 4 x 4 grid containing 4 digits preceded a sequence of 6 consonants. In the first block subjects were instructed to ignore the grid, in two remaining blocks they were asked to remember the digits or their position in the grid and to recognize them after the letter recall. In the ignore condition the expected effect of P300 decrease with letter position was found, especially at posterior electrode sites. When subjects had to process the preceding digit grid there was no position effect of P300 caused by small P300 amplitudes in the ERPs that were elicited by the first letters of the sequence. This effect was not specific to the modality of the interfering with the letter task information from the digit grid. We conclude that the grid information occupies working memory resources that are not available for the event-related processing of consonants to recall.
在最近的实验中，对7个辅音的伪随机序列进行试验后回忆（刺激开始异步时间为1000毫秒），结果显示事件相关电位（ERP）的P300波幅与字母呈现位置之间存在反向关系（格鲁内等人，1996年）。据推测，这种关系反映了在这个时间段内编码和保持过程之间的竞争。为了找到工作记忆中资源竞争假说的证据，在一系列6个辅音之前呈现一个包含4个数字的4×4网格。在第一个实验块中，受试者被要求忽略网格；在其余两个实验块中，他们被要求记住数字或数字在网格中的位置，并在字母回忆后识别它们。在忽略条件下，发现了P300随字母位置降低的预期效应，尤其是在后部电极部位。当受试者必须处理前面的数字网格时，由于序列中第一个字母引发的ERP中P300波幅较小，P300没有位置效应。这种效应并不特定于干扰来自数字网格的字母任务信息的模态。我们得出结论，网格信息占用了工作记忆资源，而这些资源无法用于对要回忆的辅音进行事件相关处理。
