Study 1

We prepared 30 hypothetical norm violation scenarios (see Table S1), two of which were adapted from a previous study45. The 30 scenarios, divided into two sets of 15 scenarios, varied in terms of outcome severity and moral domain (e.g., loyalty to one’s in-group, purity). None of the 30 scenarios involved readily identifiable victims, as it is known that empathic concern for victims causes vicarious anger, which is conceptually distinct from moral outrage46. Examples of the scenarios include Person A downloaded a large amount of music and movies for free from an online file sharing site; Person A attended a wedding ceremony wearing everyday clothes even though he/she knew that it was inappropriate; and Person A, who is an entrepreneur, moved his/her cooperate bank account to a foreign bank for the purpose of avoiding taxation. A total of 237 Japanese undergraduate students were exposed to one of two sets of 15 scenarios, and rated their emotional reactions (moral outrage, moral disgust, empathy for the depicted violator), perceived shared condemnation (What proportion of Japanese citizens do you think would condemn Person A?), and willingness to inflict two types of punishment. Two types of punitive intent were measured using hypothetical vignettes: The first vignette (henceforth referred to as ‘wallet’) was as follows: You happen to witness Person A drop his/her wallet. He/she has not yet gone far away. Would you tell him/her about the wallet? Not telling Person A about the wallet was interpreted as an informal form of punishment. The second vignette (henceforth referred to as ‘fine’) was as follows: You are entitled to impose a fine on Person A. Would you impose a fine on Person A?

For each scenario, the reported moral emotions and perceived shared condemnation were aggregated across participants. These aggregated variables are henceforth denoted as OUTRAGE k , DISGUST k , EMPATHY k , and CONDEMNATION k (the subscript k corresponds to the scenario, and thus ranges from 1 to 30). For Study 1, the uppercased variables designate scenario-level variables. In Fig. 1a, the 30 scenarios are ordered by level of average condemnation: from less consensually condemned (left) to more condemned violations (right). Each grey bar in Fig. 1a indicates the level of CONDEMNATION k , and the red, blue, and green lines indicate the levels of OUTRAGE k , DISGUST k , and EMPATHY k , respectively. As can be seen in Fig. 1a, CONDEMNATION was significantly correlated with OUTRAGE, DISGUST, and reduced EMPATHY: r 28 = 0.78, 0.58, and −0.74, respectively (all Ps < 0.001). These significant correlations indicate that more consensually condemned norm violations, on average, induced greater moral outrage and disgust, and diminished empathy for the violator.

Figure 1 Relationship between Perceived Shared Condemnation and Moral Emotions in Study 1. (a) The scenarios were ordered by the level of CONDEMNATION k (across-participants average of perceived shared condemnation for each violation scenario). The CONDEMNATION k scores are shown by grey bars. The red line shows OUTRAGE k . The blue line shows DISGUST k . The green line shows EMPATHY k . (b) The distribution of the within-individual correlation between r.condemnation jk (=j-th participants perceived shared condemnation of the k-th violation – CONDEMNATION k ) and moral outrage. The red bars indicate positive rs between r.condemnation jk and moral outrage for most participants. (c) The distribution of the within-individual correlation between r.condemnation jk and moral disgust. (d) The distribution of the within-individual correlation between r.condemnation jk and empathy. Full size image

More central to our interest, we tested whether perceived shared condemnation would predict moral emotions in each participant even after controlling for the effect of the consensual component (i.e. CONDEMNATION k ). The hierarchical linear model approach47 was employed to test this effect because 15 condemnation and moral emotion scores were nested within each participant (see SI Study 1 Method and Results for the full descriptions of the models and Tables S2, S3, and S4 for the results). The results indicated that even after controlling for the scenario effect (CONDEMNATION k ) and other potentially confounding variables (e.g., sex), condemnation significantly predicted moral emotions. In the main text, however, we opted to use the following more intuitive presentations. To remove the effect of CONDEMNATION k , we subtracted CONDEMNATION k from each participant’s perceived shared condemnation score (i.e. condemnation jk , which is j-th participant’s perceived shared condemnation associated with scenario k). This remainder score is referred to as r.condemnation jk . Positive (negative) values of r.condemnation jk indicate that the focal participant, as compared to the other participants in this study, overestimated (underestimated) the proportion of Japanese citizens (i.e., reference group) who would condemn a specific norm violation. As 15 r.condemnation jk and moral emotion scores were nested within each participant, we computed the correlation coefficient between 15 r.condemnation jk and 15 moral emotion scores for each individual (i.e., for each level of j). Figs. 1b, c and d show the distributions of these within-individual correlations for moral outrage, moral disgust, and empathy. The within-individual correlations between r.condemnation jk and moral outrage/disgust were mostly positive (see coloured bars in Figs. 1b and c) and the within-individual correlations between r.condemnation jk and empathy were mostly negative (see coloured bars in Fig. 1d). Therefore, it can be said that each individual’s perceived shared condemnation predicted the intensity of moral emotions above and beyond the actually shared component (CONDEMNATION k ).

We then examined which of the three moral emotions would predict two types of punitive behaviours (i.e. ‘wallet’ and ‘fine’). A series of hierarchical linear models was employed to test the relationship between each participant’s 15 punitive intention scores and moral emotion scores (moral outrage, moral disgust, and reduced empathy). All three moral emotions significantly predicted unwillingness to tell the violator about the dropped wallet (Table S6), whereas only moral outrage significantly predicted willingness to impose a fine (Table S5).

Study 2

Confirming the significant correlation between perceived shared condemnation and moral emotions, we proceeded to test causality. Participants (102 undergraduate students) were presented six scenarios that were associated with either medium (around 2.5 on a scale ranging from 0 to 5) or low (around 1.0) levels of moral outrage in Study 1. Each scenario was accompanied by either information indicating that the vast majority of previous participants in a similar study had considered the depicted violation ‘extremely bad’ (high shared condemnation condition), information indicating that the majority of previous participants had considered the violation ‘not terribly bad’ (low shared condemnation condition), or no information about the previous participants’ opinions (see Fig. S1 for the information given to participants). Each scenario was followed by the same measures used in Study 1 (i.e., emotional reactions, perceived shared condemnation, and punitive intentions). The experimenter explicitly told participants that the information was presented just for their reference, and they should not conform to the previous participants’ opinions.

The perceived shared condemnation measure served as the manipulation check in Study 2. As shown in Fig. 2a, the scenario outrage level (medium vs. low) had a significant effect: Participants expected greater sharedness of condemnation for the medium outrage scenarios than for the low outrage scenario (F 1, 101 = 102.48, P < 0.001, \({{{\rm{\eta }}}_{{\rm{G}}}}^{2}\) = 0.24). More importantly, participants also expected greater sharedness of condemnation in the high shared condemnation condition than in the low shared condemnation condition (F 1, 101 = 65.25, P < 0.001, \({{{\rm{\eta }}}_{{\rm{G}}}}^{2}\) = 0.18). Therefore, the manipulation was successful.

Figure 2 Mean Dependent Variables in Study 2 as a Function of Scenario Outrage (Medium vs. Low) and Information about Others’ Condemnation (High vs. Low). The dependent variables were (a) perceived shared condemnation (i.e., manipulation check item in Study 2), (b) moral outrage, (c) moral disgust, (d) empathy, (e) willingness to impose a fine, and (f) unwillingness to tell about the dropped wallet. Full size image

We then tested whether the high shared condemnation information amplified the moral emotions by a 2 (information: high vs. low shared condemnation) × 2 (scenario outrage: medium vs. low) analysis of variance (ANOVA). As shown in Fig. 2b, the main effects of information (F 1, 101 = 6.79, P = 0.011, \({{{\rm{\eta }}}_{{\rm{G}}}}^{2}\) = 0.024) and scenario outrage (F 1, 101 = 136.24, P < 0.001, \({{{\rm{\eta }}}_{{\rm{G}}}}^{2}\) = 0.332) were significant for moral outrage (Table S7). However, the effect of information on moral disgust and empathy was not significant (Fig. 2c and d, see also Table S7). For practical reasons, we only controlled for the level of moral outrage in choosing the six scenarios used in Study 2. This might have diluted the effect of information on the other two emotions. In addition, the two punitive intention scores (‘wallet’ and ‘fine’) were submitted to comparable ANOVAs. As shown in Fig. 2e, the shared condemnation information significantly increased willingness to impose a fine on the violator (F 1, 101 = 5.29, P = 0.023, \({{{\rm{\eta }}}_{{\rm{G}}}}^{2}\) = 0.021), but the effect of information was not significant for the wallet version of punishment (Fig. 2f, and see Table S8).

Study 3

Studies 1 and 2 employed hypothetical scenarios, and revealed that the intensity of moral emotions was modulated by perceived shared condemnation. To confirm the external validity, an online survey (Study 3) was conducted. In Study 3, 687 Japanese citizens reported their real-life experiences of witnessing moral violations. To examine third-party reactions to norm violations, respondents were explicitly told to report a violation in which they themselves had not been directly involved.

The online survey comprised five sections in addition to a screening section: (i) description of the violation in an open-ended format (characteristics of the reported violations are summarized in Table S9); (ii) victim(s)—the presence/absence of a victim/victims, (if a victim was present) relationship with the victim, and emotional responses to the victim; (iii) norm violator(s)—violator type (individual or group), relationship with the violator, and emotional reactions to the violator; (iv) perceived shared condemnation and indirect damage to respondents themselves; and (v) intervention and motivations underlying the intervention (for details of the survey items, see SI Study 3 Method). Demographic information (e.g., sex, age) was collected in the screening section.

In Study 3, respondents estimated what proportions of Japanese citizens and their friends would condemn the violation they had witnessed. The two estimates (one for the Japanese citizens and one for their friends) were highly correlated with each other (r = 0.72), and thus aggregated as the single perceived shared condemnation score. As shown in Figs. 3a to c (see also Table S10), perceived shared condemnation was positively correlated with moral outrage (r 685 = 0.27, P < 0.001) and moral disgust (r 685 = 0.25, P < 0.001), and negatively with empathy for the violator (r 685 = −0.09, P = 0.014). The correlations with moral outrage, moral disgust, and empathy remained significant after controlling for respondents’ sex and age, the presence of victims (either individual or collective), and indirect damage to self in a series of multiple regression analyses: βs = 0.23, 0.22, and −0.10 for moral outrage (P < 0.001), moral disgust (P < 0.001), and empathy (P = 0.010), respectively. A similar pattern emerged when we focused on violations that involved an individual victim (Table S12) and on those that did not involve any victim (Table S13)—perceived shared condemnation consistently predicted moral outrage and moral disgust.

Figure 3 Scatter Plots Showing the Relationship between Perceived Shared Condemnation and Three Moral Emotions in Study 3. (a) Moral outrage, (b) moral disgust, and (c) empathy. Full size image

We then examined whether moral emotions would predict respondents’ intervention behaviours. We conducted two separate logistic regression analyses with intervention as a dichotomous dependent variable, and moral emotions, respondents’ sex and age, the presence of victims (either individual or collective), and indirect damage to self as the predictor variables. We did not enter moral outrage and moral disgust in a single model because they were extremely highly correlated (r = 0.71, see also Table S10) and caused the multicollinearity problem. The results showed that moral outrage and moral disgust significantly increased the probability of intervention (odds ratios = 1.35 and 1.26 for moral outrage and moral disgust, respectively). Empathy for the violator significantly decreased the probability of intervention (odds ratio was approximately 0.70 in the two models; see Table S14 for more details).