Imagine one person walks into a room and they are smiling and saying hello to everyone. Then imagine another person who walks in quietly, looks grim, and heads to a corner.

Rapper Kanye West once told the press he doesn't smile for photos because "it just wouldn't look as cool," and humanities scholars who have to write about something have written that the reason Dean became cool was because he didn't smile. But is it true? 

No, unless you are under the age of 20, anyway. Across the board, a recent study showed that the person who smiled seemed more genuine and likable than the person who was inexpressive. In most cases, people who smile are regarded as being cooler. This is in contrast to the image of the aloof, quiet person as being more respected. That is why most advertising, a trillion dollar industry, has people smiling rather than being aloof. There is nothing less depressing than showing up for a dinner and finding out it is only a salad but when you see it advertised:

To test the theory, Caleb Warren, assistant professor of marketing at the University of Arizona and co-authors Todd Pezzuti from the University of Chile and Shruti Koley from Texas A&M University created several advertisements. The same endorser was depicted twice, once with a smile and once without, and people were asked to rate how cool or uncool they thought the endorser was.

"We found that the endorser seemed less cool when they were inexpressive compared to when they smiled," Warren said of the ads that included amateur and professional models, athlete Michael Jordan and Dean. "My favorite one was that even James Dean, who people have said became cool by being inexpressive, became less cool when he was inexpressive than when he smiled."

The researchers also asked people how they felt about the brand being represented, and in each case people liked the brand less when they thought the endorser was less cool.

The only time being inexpressive was deemed more cool, according to the research, was in a hypercompetitive situation. When presented with an announcement of a news conference between two mixed martial arts competitors, respondents said the inexpressive fighter was more cool than his smiling counterpart.

"In less competitive situations, the reason not smiling doesn't seem cool is because the person seems cold rather than cool, so you don't like that person. The way I interpret it is it's not so much that smiling makes someone cool as much as not smiling tends to make people less cool," Warren said. "In a highly competitive situation, the more important question is not 'Do I like this person?' but 'Is this person going to succeed in this competition?' In highly competitive situations, being inexpressive is interpreted as a sign of dominance, which is cool."