Smile study points towards cultural values
World leaders from countries which value excitement pose with bigger smiles than those which value calmness, a study has claimed.
From the ebullience of Donald Trump and Boris Johnson, to the more reserved nature of Chinese premiers, the research concluded how a culture views smiling influences how people in that culture may smile.
Psychologist Jeanne Tsai, who led the study from Stanford University, California, said in the United States the smiles of politicians tend to be big and wide, but in East Asian countries they are much more modest.
"Often people think that when they are viewing a candidate's official photo, they are learning about the candidate's unique traits," she said.
"But our findings suggest that they are also learning about the candidate's culture and the emotions it values."
Co-author Professor Joe Elliott, from Durham University, said the study illustrates how a politician like Boris Johnson would be a terrible fit for a country such as Japan.
"The real issue here is the difference in culture and what you see is a difference between the sorts of emotions that are reflected," he said.
"If you take Donald Trump or Sarah Palin, they are always bouncing around and jumping all over the place.
"But if you spoke to someone from, say, Japan their ideal would not be anywhere near as ebullient.
"These things are subtle and certain cultures value traits such as serenity and calmness. But look at someone like Boris Johnson, and he's the total antithesis of that."
The paper claims the reason behind the difference relates to a nation's "ideal affect", which is defined as culturally valued emotions and how people want to feel.
It included comparing the smiles of top-ranked American and Chinese government leaders, chief executive officers and university presidents in their official photos.
It also compared the smiles of winning vs losing political candidates and higher vs lower ranking chief executive officers and university presidents in the United States, Taiwan and China.