By Emma Young

All kinds of animals use their bodies to signal a high social rank — humans included. But a growing body of research suggests that, for us at least, there are two distinct routes to becoming a leader. One entails earning respect and followers by demonstrating your knowledge and expertise, which confers prestige. An alternative strategy is to use aggression and intimidation to scare people into deference — that is, to use dominance instead.

These two ways to the top are very different. And, to get on with their leader, an inferior-status individual would have to respond to these two types of leadership differently, too. So, reasoned, Zachary Witkower and Jessica Tracy at the University of British Columbia, and colleagues, rather than a single human high rank, “power” display, perhaps there are two distinct patterns of non-verbal behaviour that communicate to other individuals exactly what kind of leader someone is.

Their new paper, published in the Journal of Personality and Social Psychology, reveals that this is indeed the case. This is important for understanding how we display rank, and perceive and respond to it. It could also explain why studies into “power posing” have produced conflicting results.

Earlier work has found that prestigious leaders — think Barack Obama, say — tend to be empathic and helpful towards their followers, and that their willingness to share their expertise with subordinates is crucial to their status. To maintain support and devotion from their followers, such a leader would, then, need to signal not only that they have a high status but that they are also warm, caring and pro-social. In contrast, dominance-type leaders (think no end of despots) would have to also signal their aggressiveness to maintain their status.

Across many species, sheer physical size — or making yourself look bigger — sends a high-status message. In people, an “expansive” posture, with arms and legs away from the body, and the chest puffed out (which is associated with pride) has been linked to high-status, too. The team reasoned that both prestige and dominance leaders would use these postures, but that a downward head tilt (which other work has shown is intimidating) and no smile would signal dominance, while an upward head tilt and a smile would signal prestige.

Four studies that involved presenting US-based adults with either computer-generated avatars or photos of actors adopting various poses provided good evidence for this theory — raters did indeed separately associate prestige and dominance with these two distinct displays. The researchers also noted that there were no gender differences in the participants’ judgements.

For the fifth study, 191 students who didn’t know each other were assigned to 36 same-gender groups. They completed a decision-making test individually, and then were videoed while they worked on this same task in their group. Afterwards, each participant rated each of the others in their group for prestige, dominance, social influence and liking. Separately, two research assistants who watched the videos rated each for social influence. Independent coders also noted the presence, and intensity, of prestige or dominance displays in the videos.

The team found that students who adopted more obvious prestige displays were given higher prestige ratings. Also, anyone who displayed prestige was consistently judged to have exerted more influence over the group.

The results on dominance were a little more mixed: those rated higher for dominance indeed adopted more expansive stances, but were no more likely to tilt their head downwards or not smile.

The researchers also noted, however, a difference between the expansive postures used by those rated high for prestige vs dominance: prestige was associated with more chest expansion, whereas dominant students spread their limbs more — which could have the effect of making them seem more invasive of other people’s personal space.

For their final study, the team turned to videos of Hillary Clinton and Donald Trump — leaders taken to exemplify prestige and dominance strategies, respectively — during the 2016 presidential debates. Independent raters found that Clinton indeed engaged in more smiling and upward head tilting than Trump, who engaged in more downward head tilting. Also, Clinton displayed relatively more chest expansion, but Trump occupied more space, and extended his arms out from his body more.

Together, these studies “provide strong converging evidence that dominance and prestige are associated with distinct nonverbal signals which naturally emerge in ecologically valid group settings and real-world rank contests, and result in rank conferral from others,” the team writes.

The work could also help to explain inconsistencies from studies that have looked at non-verbal behaviour in relation to social rank, but not made the distinction between prestige and dominance. Given the difference that the team observed in the physical stance associated with prestige vs dominance, this might have implications for understanding power posing (which involves a combination of the two), the researchers write. “Regardless of what the future holds for power posing, researchers who seek to test this account should more rigorously consider the specific make up of the behaviours involved in the pose,” they write.

– Two signals of social rank: Prestige and dominance are associated with distinct nonverbal displays.

Emma Young (@EmmaELYoung) is a staff writer at BPS Research Digest