关键词: 厌恶情绪, 三维厌恶结构, 事件相关电位

Abstract: Disgust, an emotion motivating withdrawal from offensive stimuli, protects us from the risk of various pathogens and socio-moral violations. According to the three-domain model of disgust, pathogen disgust, sexual disgust and moral disgust are three major subtypes of the disgust emotions; disgust is considered as a heterogeneous construct consisting of multiple subtypes with distinct characteristics. Previous studies have endeavored to investigate the neural basis of pathogen disgust and moral disgust. However, it is worthwhile to systematically compare the neural underpinnings across the three subtypes of disgust with a special interest in finding out the individual differences of the disgust emotions . Therefore, in the current study, we examined the dynamic neuro-cognitive mechanisms underlying the three domains of disgust by recruiting undergraduates with different aggression level as participants. We utilized a 4 (stimulus types: pathogen disgust, moral disgust, sexual disgust, neutral) × 2 (groupss: group with high aggression level vs group with low aggression level) mixed design. The electroencephalogram (EEG) signals were recorded while participants performed a modified oddball task. The materials consisted of 40 deviant stimuli (10 pathogen disgust, 10 moral disgust, 10 sexual disgust, 10 neutral) and standard stimuli (pseudo words). Before the formal experiment, the aggression level was measured among participants by using the Buss-Perry aggression scales. Then 21 subjects were selected for the high-aggression-level group and another 20 subjects for low-aggression-level group. During the lexical decision task, participants were asked to indicate whether the visual stimulus was a word or not by pressing “d” or “k” on a keyboard with their left or right index finger. Every trial started with a central fixation for 500 ms, which was followed by a blank screen with a jittered duration between 500 ms and 1000 ms. Then the stimulus (i.e., disgust or pseudo word) was presented at the center of the screen for 2500 ms, and could be terminated by making a response. The trial ended with a blank screen with a duration of 1000 ms. We mainly analyzed ERPs elicited by pathogen disgust, moral disgust, sexual disgust and neutral deviant stimuli. The visual inspection of the grand-average waveforms suggested three time windows of interest for full analysis: 130 to 190ms, 300 to 350ms and 400 to 600ms. The mixed measure ANOVAs were conducted on the average amplitudes of the three time windows. The ERP results showed that the main effect of the stimulus types was significant for each time window. In the time window of 130-190ms, the average amplitudes of the pathogen disgust stimuli and moral disgust stimuli were significantly more positive than that of the neutral stimuli. In the time window of 300-350ms, the average amplitudes of the moral disgust stimuli was significantly more negative than that of the pathogen disgust stimuli and sexual disgust stimuli; the pathogen disgust stimuli elicited larger average amplitudes than the sexual disgust stimuli. In the late time window of 400-600ms, the average amplitudes of the sexual disgust stimuli was significantly more negative than the pathogen disgust stimuli and the moral disgust stimuli. However, the two groups with different aggression levels demonstrated very similar neural patterns when processing the three types of disgust in each of the three time windows. Thus no evident individual differences for the neural processing of disgust emotions were obtained in this study. Taken together, this study have shown that the temporal characteristics of the pathogen disgust, moral disgust and sexual disgust are distinct. The findings suggested that the three different types of disgust emotions can be identified and distinguished in the time course of processing.. On the while, we, in the current study, provideneuro-cognitive evidence for the heterogeneity of the three-domain disgust, and help to understand the neural mechanisms of the disgust emotions in a more comprehensive manner. Further studies are needed to continue to examine theneural processing of the disgust emotions in the individual level.

Key words: disgust emotions, the three-domain model of disgust, Event Related Potentials (ERPs)