Have you ever been out in public and seen someone do something outrageous? Maybe you witnessed someone yelling a racial slur at a stranger or physically abusing a young child in their care. All of us probably remember a time when someone’s behavior violated our standards of moral decency, but only some of us can say we actively intervened. What separates those who speak up from those who stay silent?

On the one hand, you might hypothesize that people who are more aggressive or hostile by nature are more likely to openly challenge a stranger. On the other hand, speaking out against injustice could be seen in a more positive light, as an act of maturity. Emerging research supports the latter idea—that people who stand up to incivility have a strong sense of altruism, combined with self-confidence. Understanding what motivates these heroic individuals could lead to more effective ways of curbing everyday immoral behavior.

Psychologist Alexandrina Moisuc of the University of Clermont Auvergne in France and her colleagues recently published findings from three studies looking at the personality profile possessed by people who say they would intervene in the face of bad behavior. Although there has been extensive research on how situational factors can impact people’s motivation to intervene (the bystander effect), there have been fewer studies looking at the role of personality.

The researchers tested two competing and equally plausible theories about who stands up: the “bitter complainer” versus the “well-adjusted leader.” The “bitter complainer” theory suggests that hostile, aggressive and insecure people are more likely to become vigilantes out of a desire to unleash displaced frustration onto an unsuspecting target. In contrast, the “well-adjusted leader” theory takes the view that people who intervene are more likely to be confident, stable and mature.

In an initial study, the researchers recruited 291 Austrian students to watch six short video clips online showing a person engaging in various types of uncivil behavior. For example, in one video the person was shown kicking a can of beer several times and then leaving it on the ground without picking it up. In another video a person is shown sitting on a bench and making an obscene gesture to a woman walking by. In all instances, the person in the video was depicted as a young man wearing regular, average clothes. After watching each video, participants rated the emotions they were feeling such as fear, disdain and disgust. These emotion ratings were combined to provide an overall measure of “moral outrage” for each participant. Next the participants were asked how they would have reacted if they had encountered the behavior in the video in their real lives. They rated the likelihood they would have done each of the following: had no reaction at all, given the person a disapproving look, made a loud and audible sigh, alerted an authority such as the police, made a disapproving comment not directly addressed to the person, made a polite comment to the person, or made an aggressive comment to the person. Participants also filled out a number of other questionnaires that measured various dimensions of their personalities such as altruism and self-esteem.

Overall, the findings seemed to support the “well-adjusted leader” theory rather than the “bitter complainer” hypothesis. People who said they would react to the behaviors depicted in the videos felt more moral outrage (stronger feelings of anger and disgust), but they did not appear to be inherently more aggressive than other people, as measured by a personality scale. Instead, they scored higher on a measure of altruism, suggesting that their motivation to act was coming from a place of wanting to help others rather than harm the person engaging in the bad behavior.

However, before drawing firm conclusions, the researchers sought to replicate and extend their findings in two additional studies that included a more diverse sample of working adults. Participants in these studies read about a greater variety of scenarios where people engaged in uncivil or immoral acts. For example, they read about a person who left dog droppings on the sidewalk without picking them up and another where a man at a public zoo hits his three-year-old son in the face. Again, participants rated the likelihood that they would say or do something in reaction to the immoral behavior. They also filled out a number of questionnaires measuring their various personality traits. Once again, the findings showed support for the “well-adjusted leader” hypothesis: participants who reported that they would have reacted in some way to the outrageous behavior showed a number of positive personality traits including self-acceptance, social responsibility and independence. They also tended to report having better control over their emotions. Also, aggression was again unrelated to the tendency to speak up, as was empathy, self-esteem, gender and occupation. Being older and having a higher salary did correlate with intervening, suggesting that feeling more secure or confident in one’s social position in society might be related to a willingness to react.

If anything, Moisuc and her colleagues seem to have found that people who stand up in the face of uncivil behaviors are the opposite of complainers. Instead they seem to possess traits that characterize upstanding citizens: a strong desire to help others, self-confidence, security in one’s place in society and maturity in handling their own emotions. Other research has supported the idea that people who intervene have a more positive outlook on others. Psychologists Aneeta Rattan of London Business School and Carol Dweck of Stanford University found that people who believe that others have the capacity to change are more likely to confront prejudice.

A major limitation of this research is that it is based on people’s self-reports rather than a measure of actual behavior. Perhaps future studies will look at the relationship between personality traits and people’s willingness to intervene in a staged scenario. However, the results remain important for helping us understand how to promote a more civil society. After all, the willingness to openly express disapproval in the face of immorality, or even step in and try to directly intervene, is often the first and most direct path toward social change.