http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011663
Way tldr.
Cliffs notes: Harvard study where participants had to call a bet or fold, and had a picture of the face of the person making the bet. There were 100 different faces. Each face had a dishonest, neutral, and trustworthy face. The study participants did this 300 times so they would play against each the 3 faces of the 100 opponents. When playing against a trustworthy face, the participants made more mistakes, often folding when calling was correct.
