【作者】 于晓琳； 陈有国； 黄希庭；

【Author】 Xiaolin Yu;Youguo Chen;Xiting Huang;School of Education Science,Jiangsu Normal University;Faculty of Psychology,Southwest University;

【机构】 江苏师范大学教育科学学院； 西南大学心理学部；

【摘要】 外部事件的时距信息在工作记忆中的神经表征机制仍不清楚。近来的相关研究均未对任务难度可能造成的干扰进行控制,导致难以确定时距信息在工作记忆中所表现出的分段性是否仅仅与任务难度有关,而非与时距长度有关。因此,本研究首先在预实验中基于韦伯定律重新设置了probe刺激条件改进实验任务,然后采用脑电图(electroencephalogram,EEG)技术结合改进后的matching-to-sample任务,在排除任务难度干扰的情况下探讨听时距保持在工作记忆中的神经表征特点。预实验结果发现,1s, 2s, 3s和4s时距条件下的时距比较正确率和反应时均无显著差异,表明改进后的实验任务已达到控制任务难度的目的。正式实验的EEG结果发现,在控制任务难度后,theta波(4-8 Hz)活动与工作记忆中保持的听时距长度无关。然而,与1s和2s时距条件相比,3s和4s时距条件下的alpha波(8-12 Hz)能量值显著降低,表明2s上下的听时距在工作记忆中的神经表征存在分段性,分界线约为2s,这为听时距的表征分段性与时距长度有关而与任务难度无关提供了有力证据。更多还原

【Abstract】 The neural representation of the duration of external events in working memory(WM) remains to be understood. Recent studies have failed to control the possible interference caused by task difficulty, which makes it difficult to determine whether the segmentation of duration representation is only related to task difficulty, not to the length of duration. In the present study, we eliminated the aforementioned limitation using a preliminary experiment in which the probe stimulus conditions were reset, while the other settings remained similar to those used in the previous study. In the preliminary study, we found that accuracy and reaction times were comparable among all the four duration conditions, suggesting that task difficulty was matched among the four conditions. In the formal experiment, theta and alpha oscillations were examined using electroencephalogram(EEG) recordings during the maintenance of the auditory duration in WM, after removing the interference of task difficulty. EEG results indicated that the theta power was not associated with the length of the auditory duration retained in WM, whereas the alpha amplitude was significantly lower in the 3-s and 4-s duration conditions than in the 1-s and 2-s conditions. The findings suggest that different internal representations of auditory durations above and below the 2-s threshold are maintained in WM. Additionally, the threshold is associated with the length of the auditory duration retained in WM but not with task difficulty.更多还原