Not only that, but the extrovert face has a smile and vivid eyes, while he introvert one has tired eyes and a concentrated "smile". Also, the competent face looks like he's paying attention, while the incompetent one does not.
Except for the trustworthy (that is female), every face seems to be decided on current expression, instead of static traits.
> while he introvert one has tired eyes and a concentrated "smile".
Who's more likely to sign up to a scientific study? An extrovert or an introvert minding their own business? I can't prove it, but it would make sense that there would be more extroverted volunteers.
The idea that I get [as an introvert] is that extroverts see introverts as depressed precisely because extroverts would likely find that lifestyle depressing. I myself find extroverts' lifestyles depressing. Given more introvert volunteers in the study you might have found that the result of that particular test may have been inverted.
The same principle may apply to all the other faces.
I don't believe the faces they showed in the article were from actual people, but an attempt to take neutral averaged faces and digitally perturb certain characteristics that have been identified as being relevant to trustworthiness or extroversion.
