High testosterone level? Don't smile when they take your picture...

You are a man, you have a high testosterone level and they are going to photograph you.
You are meant to be friendly, so you do your best to produce a warm smile. Well, that ain't gonna work.

STUDY
Psychologist James Dabbs, affiliated with Georgia State University in the US, had 19 men and 14 women photographed twice by a friendly and attractive undergraduate.
For one photo the test subjects had to pose smiling, for the other not. At the same time, Dabbs determined the testosterone concentration in the saliva of the test subjects The psychologist had the photos assessed by a panel.

Results
For all the photos, the panel had to say whether they found the people in the photo strong/dominant, active or friendly/good.

Below you can see what the panel thought of the photos in which the men and women with a high testosterone concentration were smiling and serious. The higher the percentages, the more often the panel rated a photo of someone with a high testosterone as strong/dominant, active or friendly/good compared to the men and women with a low testosterone concentration.

For women, those associations were not there.

When Dabbs analyzed the photos, he saw that the muscles involved in a smile worked less hard in men with a lot of testosterone.

Explanation
According to Dabbs, men with a lot of testosterone want to dominate situations. They want to exercise control. They don't have this control when a photographer captures their face forever. The stress of this situation makes their smiles not genuine.

For women it is slightly different. According to Dabbs, women with a lot of testosterone want to dominate just as much as men with a lot of testosterone. The fact that you can't tell by their smile whether they feel uncomfortable is because women in our culture smile more often than men. So they have more exercise than men.

Source:
Journal of Nonverbal Behavior. 1997;21(1):45-55.