An experimental study published in Biological Psychology explored how the facial expressions we direct at others influence the way we feel about the expressions we receive back. Participants rated smiling virtual agents as most pleasant after they themselves had initially smiled at the agent (versus frowned).
Facial expressions are fundamental to how we communicate and interact with one another. For example, our expressions help convey our intentions within social interactions. A smile can suggest a desire to bond with another person while an angry expression can communicate threat.
Psychology studies have explored how people process and react to facial expressions, usually in a one-way direction. For instance, studies have assessed how observers evaluate frowning or smiling faces. But study authors Leon O.H. Kroczek and Andreas Mühlberger point out that facial expressions are shared reciprocally — for example, one person smiles at another person and the other person usually smiles back. Therefore, the authors designed an interactive paradigm to explore the social processing of facial expressions within a reciprocal exchange.
Specifically, Kroczek and Mühlberger tested how sending a particular facial expression to another person might influence the sender’s evaluation of the facial expression they receive in return. To do this, the researchers first recruited 68 university students to partake in the experiment. The students were shown video clips of animated virtual agents showing neutral facial expressions. Depending on the condition, the participants were prompted to direct either a happy, angry, or neutral expression to the agent. The agent then responded with either a happy or an angry expression in return.
Following 20% of the trials, participants were asked to rate their level of emotional arousal and their level of pleasant feelings toward the virtual agent. To assess participants’ reactions on a physiological level, electromyography (EMG) was used to measure activity in two facial muscles, the M. zygomaticus major (a muscle group activated when smiling) and the M. corrugator supercilii (a muscle group activated when frowning).
The results revealed that agents who returned a happy expression to the participants were rated most pleasant when the participants had initially smiled at them. Smiling agents were rated as least pleasant when subjects had initially displayed an angry expression. Further, agents who returned an angry expression were rated as most pleasant when the participants had initially frowned at them compared to smiling or showing a neutral expression. Notably, these findings reveal that participants’ ratings of the smiling and frowning agents were influenced by the initial facial expressions that participants were asked to direct to them.
The subjects rated the interactions as most emotionally arousing when they began the interaction with a smile and least arousing when they began it with a neutral expression. The agents’ response expressions did not influence the students’ arousal ratings.
There was also evidence that the initial facial expressions impacted the students’ physiological responses. When participants began the interaction with a smile (compared to a frown) they showed greater Zygomaticus activation when the agent sent them a smile back (compared to a frown). Corrugator activation was also greater when the agent responded with an angry compared to a happy expression, but this effect was not influenced by participants’ initial expressions.
The researchers say that their findings showcase how facial expressions are interdependent and that people interpret others’ facial expressions differently depending on the social context.
“When a facial emotional expression is perceived as a response towards one’s own behavior, the expression may gain meaning beyond the meaning of the isolated facial expression,” the study authors explain. “For example, when a smile follows an initial smile, this can indicate that a person’s affiliative intention is reciprocated by the other person, whereas when a person responds with a smile to an initial angry expression this may indicate conflict avoidance.”
A limitation of the study was the use of an experimental paradigm rather than observing a spontaneous interaction between two people. Participants were prompted to direct particular facial expressions toward agents, and it is unknown whether they perceived the agents’ expressions to have been evoked by their own.
The study, “Returning a smile: Initiating a social interaction with a facial emotional expression influences the evaluation of the expression received in return,” was authored by Leon O.H. Kroczek and Andreas Mühlberger.