From self-interest to group interest: Machiavellianism fuels intergroup bias depending on ingroup identification

The fact that Machiavellianism entails a preference for oneself over others has been well documented. However, whether this self-centeredness extends to a tendency to favor one's ingroup over outgroups remains unanswered. By integrating social identity theory with the Machiavellianism literature, we propose and test the hypothesis that Machiavellianism leads individuals to favor their ingroup over outgroups (a phenomenon known as intergroup bias) among individuals who identify strongly with their ingroups. Study 1 (N _{country =} 43), which relied on data drawn from the World Values Survey and the Open Psychometrics Project, provided both national-level and cross-level evidence supporting our hypothesis. Study 2, which surveyed 400 Chinese university students, supported the hypothesis at the individual level in inter-university contexts. Study 3, which involved a preregistered survey of 374 Americans, confirmed our findings in both interracial and interparty contexts. Study 3 also revealed that among high (vs. low) identifiers, Machiavellianism positively predicted intergroup bias by reducing negativity toward the ingroup. Our findings extend Machiavellianism research by linking it to intergroup bias, offering theoretical and practical implications from an intergroup perspective.