The aim of the present study was to demonstrate the effect of verbal ratings on arousal in the electroencephalogram (EEG) and psychomotor vigilance test (PVT) performance. Thirty participants underwent the PVT for 40 min in three experimental conditions: (1) Rating condition, in which they verbally rated subjective sleepiness with Karolinska sleepiness scale, following pure tone sound played every 20 s during PVT, (2) No-rating condition, in which they underwent PVT with the similar sound as the Rating experiment but without the verbal rating task, and (3) Control condition, in which they underwent PVT with a no-sound stimulus and without the verbal rating task. The results show that during the first half of the task epoch, alpha power density was lower in the Rating than in the No-rating condition, while performance was not different between the conditions. During the second half of the task epoch, performance was better in the Non-rating than in the Rating condition, but no difference in the alpha power density. These results suggest that performance deterioration could be masked by the arousal effect of the dual task itself. It could also explain why the PVT performance and arousal in EEG sometimes dissociate, particularly in dual task situations.

本研究的目的是证明脑电图（EEG）和心理运动警惕性测试（PVT）表现中言语等级对唤醒的影响。30名参与者在以下三个实验条件下进行了40分钟的PVT：（1）评定条件，在PVT期间每20 s播放一次纯音之后，他们用Karolinska嗜睡量表对主观嗜睡进行评分，（2）无评定条件，其中，他们以与评定实验相似的声音接受PVT训练，但没有口头评定任务；以及（3）控制条件，他们接受无声音刺激且没有言语评定任务的PVT。结果表明，在任务时期的前半段，Rating中的α功率密度低于No-rating条件下的功率密度，而条件在两个条件下没有什么不同。在任务时期的后半段，非评级比评级条件下的性能更好，但alpha功率密度没有差异。这些结果表明，双重任务本身的唤醒效果可以掩盖性能下降。这也可以解释为什么脑电图中的PVT表现和唤醒有时会分离的原因，特别是在双重任务情况下。