Embodied Emotion Theory:Evidences From ERP And FMRI

Recently, embodied cognition has acquired more and more attention, and gotten a number of supports from many psychological fields, for example, emotion, cognitive evaluation and language. When embodied cognition was induced to emotion cognition, embodied emotion theory emerged. The embodied emotion theory thought that the processing of emotional messages was not merely signal processing, but the body played a very important role. In more details, body state and the way of activity laid the foundation for the processing and understanding of emotion messages. Since appearing, embodied emotion theory got supports from some experiments. However, many traditional cognitive psychologists were still skeptical to its main viewpoints. Embodied emotion theory still needed more experiments to verify it, especially through some more advanced techniques, for example, the time-related potentials (ERP) and functional magnetic resonance imaging (fMRI). After checking the literature, we found that the empirical researches about embodied emotion theory mainly concentrated in foreign countries, and most of them were behavioral researches, rarely on the neural mechanism of embodied emotion. Moreover, the studies that carried out under the background of Chinese culture were almost none. Therefore, our study adopted ERP and fMRI as experimental methods to discuss the neural mechanisms under the judgment of emotional facial expressions when holding a pen with mouth or teeth. Through this experiment we tried to provide evidence for embodied emotion theory.In study1, the spatiotemporal pattern of brain activation during judgment of facial expressions (happy and neutral facial expressions) under different emotional facial postures [holding a pen using only the teeth (HPT); holding a pen using only the lips (HPL)] was investigated using high-density event-related brain potentials (ERPs). Results showed that Happy facial expressions under HPL (inhibiting the muscles typically associated with smiling) elicited a more negative component (N220-250) than did HPT (facilitating the muscles typically associated with smiling) between220and250ms, which might reflect monitoring conflict between potential facial muscles due to automatic happy facial expressions simulation and sustained facial muscles activated by HPL during early perception of facial expressions. Furthermore, Happy facial expressions under HPL elicited a smaller positive component (P450-550) than did HPT in the time window of450-550ms, which might reflect resolving the conflict effectively and making a judgment of the facial expression. However, these ERP effects (N220-250and P450-550) were not found for Neutral facial expressions. These results might support embodied emotion theory that the processing of emotional messages needed the imitation of own body and the changes of body state could affect the entire process.In study2, we used event-related functional Magnetic Resonance Imaging (fMRI) to investigate the brain activation during judgment of facial expressions (happy facial expressions and sad facial expressions) under HPT (happy facial posture) or HPL (sad facial posture). Our fMRI results showed that:compared with the inconsistent conditions (Happy facial expressions under HPL; Sad facial expressions under HPT), the consistent conditions (Happy facial expressions under HPT; Sad facial expressions under HPL) showed significant enhancement activation in the left supplementary motor area and the inferior parietal lobule (IPL), which both were posited as parts of the human "mirror neuron" system (MNS). This result indicated that the facial posture might affect the processing of emotional information. The body state could promote or reduce the imitation of emotions presented, if it was consistent or inconsistent with the emotional valence required to judge.Nevertheless, study1and study2confirmed each other, completed each other, and jointly supported the embodied emotion theory. Firstly, the judgment of emotional facial expressions was not simply signal processing, but needed the body to join in. during the processes of perception and understanding of emotional information needed the body to imitation. Secondly, if the physical condition (the state of facial muscles) was inconsistent with the emotion valence which required to be recognized, it would affect the imitation of this emotion, expressed as the reduced activation of mirror neuron system and the emergence of electrophysiological components about conflict (N2/P3).