Men with wide faces are more likely to express racially prejudice views, according to US research.
Past studies have shown facial width-to-height ratio (fWHR) is associated with testosterone-related behaviours, which some researchers have linked with aggression.
However psychological scientist Eric Hehman of Dartmouth College and colleagues at the University of Delaware speculate these behaviours may have more to do with social dominance than outright aggression.
The researchers examined the relationship between fWHR and dominance in the specific context of racial prejudice.
"Racial prejudice is such a sensitive issue and there are societal pressures to appear non-prejudiced. More dominant individuals might care less about appearing prejudiced, or exercise less self-regulation with regard to reporting those prejudices, should they exist," says Hehman.
The researchers asked male participants about their willingness to express racially prejudiced beliefs and about the pressure they feel to adhere to societal norms.
The results revealed those men who have higher fWHR (determined from photos of their faces) are more likely to express racist remarks and are less concerned about how others perceive those remarks.
The findings have been published in the Association for Psychological Science's journal, Psychological Science.
The results did not show that these men were necessarily more prejudiced - men with greater fWHR did not score higher on measures that assessed implicit racial prejudice. Rather, these men were simply more likely to express any prejudicial beliefs they may have had.
"Not all people with greater fWHRs are prejudiced, and not all those with smaller fWHRs are non-prejudiced," says Hehman. "You could think about it as a 'side effect' of social dominance - men with greater fWHR may not care as much about what others think of them."
Results from a second study suggest that observers actually perceive and use the facial width-to-height ratio when evaluating another person's degree of prejudice.
Looking at the photos from the first study, a new group of participants evaluated men with wider, shorter faces as more prejudiced, and they were able to accurately estimate the target's self-reported prejudicial beliefs just by looking at an image of his face.
The researchers said the studies add to a growing literature exploring how people perceive and accurately infer personality characteristics based on physical appearance.
"This research provides the first evidence for a facial metric that not only predicts important and controversial social behaviors, such as reporting prejudices, but can also be used by others to make accurate judgments," says Hehman.