An ERP Research Of Exploring Early Mechanism Underlying Moral Intuitions

Moral judgment refers to the mental process that we use the existing moral values and moral knowledge to analyze moral phenomena. In the fields of cognitive psychology, the mechanism of moral judgment has been the focus of attention, while the nature and function of cognitive inference and intuition(emotion) during machining of moral judgment remains a controversial issue.Early researchers viewed the moral judgment as a conscious process of cognitive inference. But recent studies have found that the process of moral judgment include not only cognitive inference, also an early automatic process, that is, moral intuition. Therefore, it is very significant to research the process(particularly the early processing stages) of moral judgment from the perspective of time course. In fact, recent studies on the temporal features of moral judgment have consistently found that brain will be able to recognize moral information in the early stage, which to a certain extent reflect the function of moral intuition. However, there are still several defects(for example, it is difficult to exclude the effect of visual composition and the physical properties of stimulates on the early ERP components) in the available research paradigms, which lead to the reliability of experimental results be questioned. Therefore, in order to reduce the effect of irrelevant factors on the early processing of moral judgment, this study uses a paradigm named rapid stream stimulation(RSS) and the high time resolution ERPs(event-related potentials) technique to investigate whether there actually is moral intuition in the early processing of moral judgment, which help people to recognize and process the moral information quickly.In particular, using the RSS paradigm, this experiment quickly, alternatively, randomly presents the subjects some identifiable stimuli(4 species, including words about moral violation, pure disgust, neutral words and country names or place names) and unrecognized materials(background stimulus) with the speed of 250 ms each stimulus. The task of participants is quickly pressing “1” key when they see the country name or place name. RSS paradigm will induce recognition potential(RP), and RP is usually believed to reflect early semantic processing, and moral judgment must be involved semantic processing firstly. Therefore, we treat RP as the indicator to explore the early temporal features of moral judgment by comparing the differences of RP amplitude induced by the 3 types of material(words about moral violation, pure disgust and neutral words). Then, we use the disgust sensitivity scale and moral foundations questionnaire(MFQ-30) to measure the subjects hoping to explore there are or not individual differences in the early processing of moral judgment.The ERP results showed that there are 2 different trends of RP between subjects. The results of a group(12 subjects, moral group) showed that those words about moral violation induced greater RP amplitude relative to those words about pure disgust and neutral words; the results of another group(15 subjects, disgust group) showed that those words about pure disgust induced greater RP amplitude relative to those words about moral violation and neutral words. The results of questionnaires showed that moral group scored higher in the care/harm subscale of MFQ-30 than disgust group and scored lower in the pathogen disgust subscale of the disgust sensitivity scale than that of the latter. Combining 2 results, we found that RP amplitude of moral group who are more sensible to moral information(especially information associated with harm) than disgust group appeared to recognize moral information preferentially; and RP amplitude of disgust group who are more sensible to pathogen disgust information than moral group appeared to recognize disgust information preferentially.The results of this study showed that the separation of RP induced by moral and non-moral information revealed that brain actually be able to quickly recognize moral information in the early stage, which may reflect the function of moral intuition. However, there may be individual differences in the early processing of moral judgment. It may be due to the differences of moral sensitivity and disgust sensitivity in different individuals, but the specific mechanisms required further exploration in the future.