Abstract: Intertemporal choice requires people to trade-offs between costs and benefits that occur at different points in time. In real-life situations, emotional experiences are ubiquitous. Many decisions need to be made in a variety of incidental emotional states that are independent of decision-making tasks. Most researchers have taken a valence-based approach to examine how incidental emotions affect intertemporal choice. Recently, there has been an increased interest in investigating the influence of incidental specific emotions on intertemporal choice. However, few studies explore whether distinct emotional states of the same valence might have different effects on intertemporal choice. Disgust and fear are two kinds of negative emotions that are common in life. Although there were similar emotional valence and arousal level, disgust and fear are distinct in many aspects. First, their biological meanings are different. Second, their physiological bases are different. Third, their cognitive functions are different. Therefore, the present study focused on the effects of disgust and fear on intertemporal choices by using event-related potential techniques (ERPs). Twenty healthy volunteers participated in the present study. Disgust and fear were primed by emotional face images which were selected from Taiwanese Facial Expression Image Database (TFEID); We administered a modified version of intertemporal choice task, in which participants made a series of hypothetical choices between immediate rewards and delayed rewards. This study recorded and then analyzed the differences of ERP components in the evaluation stage of intertemporal choice task, thereby examining the processing mechanisms of disgust and fear affecting intertemporal choice. The behavioral results showed that disgust prime yielded significantly higher percentage of immediate reward choices than neutral prime. The ERP results showed that during the evaluation stage, disgust prime evoked larger P2 and P3 than neutral prime and fear prime; For the LPP, disgust prime evoked a larger LPP than neutral prime and fear prime in left and center electric sites, whereas disgust prime evoked a larger LPP than fear prime in right electric sites. In the present study, the longer the reward wait time, the greater the risk that is not available, and the delayed reward is considered as a risky, incomplete option. Therefore, disgust prime induced individuals to avoid risks and losses, and thus prefer to choose immediate rewards. Previous ERP studies on cognition and decision-making showed that the P2 might reflect stimulus evaluation and aquick assessment, and the P3 and LPP is regarded as a measure of motivational significance in the decision-making literature. In the present study, the larger P2, P3, and LPP in disgust prime might be correlated with the motivational evaluation process involved in the integration of time and reward information. In conclusion, the present study found that disgust prime motivated individuals to prefer immediate rewards, whereas fear prime did not change the choice preference. For the ERP results, there were different in the P2, P3, and LPP during the evaluation stage. These findings suggest that relative to neutral and fear prime, disgust prime motivates individuals to place more attention and motivation renounces to evaluate the choices, and then makes them to choose the immediate rewards.

Key words: disgust, fear, negative emotion, intertemporal choice, ERP

摘要： 本研究运用事件相关电位技术(ERPs)考察厌恶和恐惧情绪对跨期选择的影响。其中，厌恶和恐惧情绪采用情绪面孔图片进行启动，分析跨期选择任务中评估阶段所诱发的ERP成分。行为结果发现，与中性面孔相比，厌恶面孔启动使个体倾向于选择立即奖赏。ERP结果发现，在选项评估阶段，厌恶面孔比中性和恐惧面孔启动诱发更大的P2、P3和LPP波幅。这说明，厌恶情绪促使个体投入更多的注意和动机资源对跨期选项进行评估，进而使个体倾向即时满足。

关键词: 厌恶, 恐惧, 消极情绪, 跨期选择, ERP