Abstract: Emotion suppression is a form of emotion regulation defined as the conscious inhibition of emotionally expressive behavior while emotionally aroused. Previous research has shown that inhibiting emotionally expressive behavior leads to depletion of self-regulatory capacities and increased sympathetic activation of the cardiovascular system. Evidence from decision-making research has indicated that the cognitive-affective component was modulated by the attributes of options when making choice. This process was monitored by the individual and required an effort of self-regulation. Drawing from a limited-resource model of self-regulation, we predicted that emotion suppression would impact the subsequent decision making task due to the depletion of the self-regulatory capacity.
The study was designed to investigate the effects of emotion suppression and its influence on the behavioral responses of respondents in the ultimatum game, using methods of psycho-physiological experiments. Participants were 20 female and 20 male college students. Ten negative pictures were presented to all the participants. Half of them were instructed to suppress their emotions and the other half simply watch the pictures, and then all the participants were instructed to play as the responders in the ultimatum game presented on the video monitor. Physiological measures were collected continuously throughout the whole procedure. Emotional states before and after watching the pictures were assessed by using a self-report inventory, which contained 5 emotional states: amusement, anger, disgust, fear and sadness. The experimental design was a 2×2×4 mixed factorial, in which group condition (no-suppression, suppression) varied between subjects, and game rival (human, computer) as well as money proposals (￥5：￥5、￥7：￥3、￥8：￥2、￥9：￥1) varied within subjects.
The results showed that: (1) the Repeated Measure ANOVA for the self-report variables did not reveal any effects with respect to group condition, indicating that the suppression instructions did not impact the emotion self-reports. (2) participants under the suppression condition showed more increases in skin conductance, however, the heart rate did not show the significant differences across the suppression manipulation. (3) there were no sex differences in the effects of suppression. (4) the interaction between group condition and money proposals on subjects’ acceptance rate in UG was found, which indicated that the behavior of the game players as they responded to an unfair proposal was influenced by suppression manipulation.
In conclusion, the present study demonstrated that suppression had no effect on self-reported experiences of negative emotions. Inhibiting negative emotion-expressive behavior led to increased sympathetic activation characterized by increased skin conductance activity. Emotion suppression had a significant influence on the UG decisions: participants in the emotion suppression condition, when faced with unfair offers, were more likely to refuse the offer.

Key words: emotion suppression, the ultimatum game, decision-making, skin conductance activity, heart rate