在认知任务中,结果评价阶段由负性反馈信息诱发的ERP相对于正性反馈信息诱发的ERP,表现出一个相对负走向的波形变化,称为反馈负波(Feedback Negativity,FN)。实验采用模拟现实生活中替人点钞情境中的欺骗行为作为任务,要求被试对看到的人民币图片按键报告其真假,同时对其中的真币图片可以做出欺骗性反应,即故意报告其为假币并力争“欺骗”计算机,从而创造出欺骗失败减钱和欺骗成功加钱两种不同效价的结果。并通过1元、5元和10元三种不同面额的人民币图片,考察FN是否反映对结果信息中得失量的评价,以及不同预期强度水平对FN的影响。结果发现,FN只受结果效价、而不受数额或预期强度水平的影响。此外,FN的发生源可能位于扣带前回附近。实验结果支持了FN的现代二分理论,说明FN可能反映了基于结果与预期是否一致方面的“好”、“坏”简单快速评价。
Outcome evaluation is one of the important functions of the cognitive system. It can provide rapid and efficient information about the outcomes of one' s behavior in order to facilitate the performance of the behavior. Recently, researchers have shown great interest in the neural mechanisms of outcome evaluation. Many studies have confirmed that a significant ERP component, called feedback-related negativity (FN), could be elicited by negative performance feedback compared to positive outcomes. The purpose of this study was to investigate the mechanisms of the outcome evaluation reflected by FN and to explore whether FN is affected by the magnitude information carrying different intensity levels of the expectation. To observe the outcome evaluation following complex cognitive processes, a deception task was conducted in a simulated experimental situation involving the identification of currency. The participants were required to identify pictures of genuine Renminbi (RMB) from a set of pictures of fake ones. The participants were asked to press the left key to indicate genuine RMB pictures and the right key to indicate fake ones. However, we told them that for each genuine RMB picture, they could decide whether to "declare" (tell the truth) or "smuggle" (lie) and that telling the truth would result in them receiving a small but certain monetary reward, whereas lying may lead to a potential gain if they escaped being caught or a risk of double penalty if their lie was detected by the software. Seventeen healthy undergraduates who had never participated in any electroencephalography (EEG) experiment before volunteered for this study. The EEG was recorded from 64 scalp channels using electrodes mounted in an elastic cap. Feedback-related ERPs were calculated for an 800ms epoch including a lOOms pre-feedback baseline. The outcome valences (gain when deception was successful and loss when deception was unsuccessful) by the magnitudes (pictures of the RMB worth 1,5, and 10) resulte