时间估计任务中的反馈加工和行为调节:来自ERP的证据

Performance Monitoring and Behavioral Adjustments in a Time-Estimation Task:Evidence from ERP Study

本研究采用时间估计任务,利用高时间分辨率的ERP技术,试图从时间进程上窥探行为调节的认知神经机制。该时间估计任务提供了指导行为调节的反馈信息有三类:时间估计的准确性、时间估计的不准确方向和不准确程度。行为结果表明,被试根据前次时间估计的对错、不准确的方向和程度进行相应的调整。脑电成分发现,FRN对于时间估计的对、错敏感,对时间估计的不准确的方向和程度不敏感,显示FRN提供了粗略的、需要做出行为调节的早期预警信号;相反,P300能够区别时间估计上不准确的方向和程度,结合行为数据,显示P300反映的是整合不同的信息来更新行为表征,从而引导被试做出不同方向和不同程度的调节。这些结果表明,行为调节的认知神经基础可能由两个阶段组成:早期传递需要做出行为调节的预警信号阶段和晚期整合信息来更新行为表征从而指导行为调节的阶段。

It is important for successful future behavior to learn from past mistakes. In the last two decades, performance monitoring has received a lot of attention. Some studies showed that the FRN （feedback related negativity） was sensitive to adjustment behavior following the feedback stimulus, whereas some studies did not find any relationship between ERN amplitude and behavioral adjustments. So it is unclear how the brains learn from past mistakes. In the present study, we used a time-estimation task with feedback type （correct, incorrect-slow, incorrect-fast with the graded incorrect feedback as a function of the degree of error under gain and loss condition. Event-related potentials were recorded to explore the neural mechanism of the performance monitoring and behavioral adjustment in time-estimation task. Thirteen healthy volunteers participated in this study. Subjects were asked to estimate a 1-second interval and feedback was based on the estimation of the participants. Subjects received graded incorrect feedback as a function of the degree of error and the ＇punishment＇ on incorrect trials was loss 30 Yuan, loss 20 Yuan, or loss 10 Yuan relative to correct trials. Analyses of the behavioral data revealed that the subjects shortened or lengthened their judgments according to feedback and the amount of adjustment was related to the suggested degree of error. Behavioral data indicated that the subjects made use of the information provided by the feedback in adjusting their behavior from one trial to the next. Analyses of ERP data focused on feedback-related negativity （FRN） and P300. FRN analyses revealed that FRN was sensitive to feedback value but insensitive to fast-slow incorrect feedback or three punishment levels. These results suggested the dissociation between the processes underlying generation of the FRN and the processes responsible for behavioral adjustments. P300 showed an opposite pattern relative to FRN： P300 was modulated not only by fast-slow incorrect feedback but also by the three incorrect levels. Post hoc tests confirmed that P300 became larger in the order of Loss 10 Yuan 〈 Loss30Yuan whether in the gain or the lose condition as verified by the behavioral results. In this case, the additional information provided in the time estimation task would be used by systems that produced the P300 to update reward expectations and to guide adaptive decision making. Thus, P300 is taken as an index of the updating of action representation and a brain potential of behavioral adjustment. These findings suggest that brain responses in performance monitoring and behavioral adjustment may be divided into an earlier rapid, semi-automatic, alerting process which indicates that behavioral adjustments are needed and a later slower, conscious cognitive appraisal process which indicates updating of action representation that vary as a function of current contexts and processing goals.