Introduction: Implicit biases of health professionals could cause biased judgements. Many anti-bias interventions seem to be ineffective, and some even counterproductive. People tend to be compliant to standards describing what the majority of people finds or does, and this could cause people to think in a stereotype-consistent manner. This study examines whether descriptive social norms such as ‘the majority of people have stereotypes’ (majority message), as often stated in interventions, actually increase people's stereotypes. To examine the effect of descriptive social norms (Hypothesis 1) and the effect of individual perceptions and preferences (Hypothesis 2a and 2b) on stereotypical expressions towards medical students. Methods: First, we determined which ethic stereotypes regarding medical students prevail in Dutch medical education (N = 52). Next, two similar randomised controlled trials, both with teachers and students, were carried out (N = 158 and N = 123, respectively), one with an East Asian student picture (ethnic minority) and one with a native Dutch student picture (ethnic majority). Participants were randomly assigned to either a majority-message, minority-message or no-message condition, and rated the presented minority or majority picture on specific stereotypical features. Subsequently, participants described a typical day of that same student's life. These descriptions were rated for stereotypicality by two independent raters, who were blind for condition and stimulus. Inclusive work environment (IWC) and social dominance orientation (SDO) of participants were measured as indicators of individual perceptions and preferences. Results: Stereotypes were expressed towards both picture stimuli, yet message condition did not affect stereotypical expressions. SDO positively related to stereotypical expressions towards the East Asian student, whereas IWC positively related to stereotypical expressions towards the native Dutch student. Conclusion: Interventions do not unintentionally increase stereotypes by communicating what the majority of people thinks or does. Individual perceptions and preferences are predictive of stereotypes, whereas descriptive social norms are not.