Though smiling generally increases trust, new research provides evidence that it can backfire for people with certain antisocial personality traits. The study, published in PLOS One, examined how personality traits and facial expressions interacted to influence perceptions of trustworthiness.
Previous research has found evidence that smiles increase cooperation while signs of personality disorder decrease cooperation. But what happens when smiles are combined with indications of pathology?
“I’ve had two lines of research in my career thus far. One investigates the communicative functions of facial expressions and the other investigates personality disorders. Here, I was able to combine these two lines by examining how people interact to others when given information about their emotional state (via their facial expression) and personality traits,” said study author Lawrence Ian Reed, a clinical assistant professor at New York University.
In the study, 262 participants were asked to play an economic investment game with another person. In reality, the other person was an invention of the researchers.
The participants read a brief description of the person, which described them as having traits consistent with either borderline personality disorder, antisocial personality disorder, or no personality pathology. These descriptions were paired with a brief video clip that showed them with either a neutral expression or a smile.
In the investment game, each participant was given $0.50 and was free to decide how much of that money he or she would give to the other person. The participants were informed that any amount given to the other person would be tripled. The other person would then either share back some of what they received or keep all of it. The money transferred by the participant to the other person served as an indicator of trust.
The researchers found that both smiles and personality traits influenced trust.
The participants tended to transfer less money when the other person was described as having borderline personality disorder or antisocial personality disorder in comparison to those described as having no personality pathology. Smiles increased the amount of money transferred for both those described as having either borderline personality pathology or no personality pathology, but decreased the amount transferred for those described as having antisocial personality pathology.
The findings indicate that “both your emotional state and your personality traits affect the ways that people perceive you and interact with you. Depending upon your personality, a smile can increase or decrease how you are perceived and treated by others,” Reed told PsyPost.
“In most cases, a smile makes someone appear more trustworthy. However, when displayed by an individual with antisocial traits, a smile can make them appear less trustworthy. Think the Joker or some other conniving character.”
In a follow-up with another 283 participants, the researchers repeated their experiment with slightly altered descriptions of the other person’s personality. They mostly replicated their results. However, this time around, smiles increased the amount of money transferred to those who were described as having antisocial personality pathology.
The findings suggest that how smiles influence the perception of trust “depends upon which antisocial traits are present,” Reed said.
The first experiment described the antisocial person as being disobedient, a frequent liar, and violently argumentative. The second experiment described the antisocial person as being remorseless, impulsive and reckless.
“There is great heterogeneity among those with antisocial personality disorder and only some variants have this effect. We’re hoping to find out which variants have this effect in the future,” Reed said.
“I’d like to note that although the smiles used in this study were posed, they were of the same muscular configuration and timing of a felt, genuine smile. That is, they included the zygomaticus major muscle pulling the lip corner upwards and the orbicularis oculi muscle raising the cheeks. There are many types of smiles and this is something that we might look into in the future,” he added.
The study, “In smiles we trust? Smiling in the context of antisocial and borderline personality pathology“, was authored by Lawrence Ian Reed, Ashley K. Meyer, Sara J. Okun, Cheryl K. Best, and Jill M. Hooley.