The facial-feedback hypothesis states that the contractions of the facial muscles may not only communicate what a person feels to others but also to the person him- or herself. In other words, facial expressions are believed to have a direct influence on the experience of affect. This hypothesis goes back to Charles Darwin, who wrote that the expression of an emotion intensifies it, whereas its repression softens it. A second origin of the facial-feedback hypothesis is William James’s theory of emotion, which states that the bodily changes follow the perception of an exciting fact and that the feeling of these bodily changes is the emotion.
Although Darwin and James differ in their view of the role of the eliciting stimulus, they agree that the behavior that accompanies an emotion exerts a causal influence on its experience. In particular, the skeletal muscles were identified as important contributors. While Darwin has assigned the facial muscles a special role as means of expression and has meticulously described their evolutionary significance (e.g., frowning), James’s account is based on more global units of behavior (e.g., running away).
To test the causal influence of facial expressions on the experience of affect, three different procedures have been employed. In some experiments, participants were explicitly instructed to adopt an emotionally relevant facial expression. In another set of studies, the emotional meaning of the expression was not mentioned. Instead, the experimenter would point at the muscles that were supposed to be contracted. In yet a third method, facial expressions were induced by a procedure that required the contraction of specific muscles for a purpose that was void of any emotional meaning. For example, participants were told to hold a pen with either their teeth or their protruded lips to either induce or inhibit a smiling expression by extracting the zygomaticus muscle (one of the main muscles involved in making the mouth into a smile) or its antagonist. In a related study, golf tees were fixed on people’s foreheads, which they had to move together by contracting the corrugator (frowning) muscle.
All procedures were successful in causing affective consequences either in people’s self-reported mood, in specific emotions, or in the evaluation of emotional stimuli, like cartoons. However, the three facial-induction methods afford different theoretical interpretations. Specifically, the more likely it is that the induction of the facial expression is linked to the recognition of its emotional meaning, the more likely it is that people may infer their affective state on the basis of their expression. For example, they may draw the inference that if they smile, they must be amused. This mechanism is an extension of Bem’s self-perception theory, which assumes that if internal cues are weak or ambiguous, people infer their attitudes from their behavior. Similarly, they may infer their emotional states from what they do. However, the fact that affective consequences can be obtained from facial expressions even if their emotional meaning is disguised suggests that more direct mechanisms may be operating as well.
While self-perception theory may account for the cases in which the meaning of the expressions is apparent, other models are necessary to explain the direct impact of the facial action. On a physiological level, it has been argued that facial expressions may regulate the volume and particularly the temperature of the blood that flows to the brain and therefore influence cerebral processes. It was suggested that an emotional event may cause peripheral muscular, glandular, or vascular action that changes the emotional experience. Another explanation that is based on evidence from the neurosciences comes from a study that identifies specific cortical activities that are connected to different facial expressions. Specifically, it was found that the facial expression of emotions that are linked to approach (e.g., joy) were associated with greater left frontal brain activity while avoidance emotions (e.g., fear and anger) were linked with greater right frontal activation.
From a more psychological perspective, the effects of facial feedback can be understood as the result of a motivational orientation. As an example, one theory assumes that behaviors that are involved in approach facilitate the processing of positive information, whereas behaviors that are involved in avoidance facilitate the processing of negative information. Applied to facial expressions, this implies that a smiling expression will facilitate the processing of a cartoon and therefore intensify its affective impact. This also explains why, in many studies, the mere adoption of an expression has by itself had no emotional effect.
The importance of facial feedback has been recognized in domains that go beyond the emotional experiences. For example, it has been found that positive or negative sentences are understood more easily if, outside of their awareness, people were led to adopt a facial expression that corresponded to the valence of the sentence. In one study, research participants had to hold a pen in the smiling pose while watching photos of either White or Black people. As a consequence, implicit racial bias was reduced. Also, the importance of facial feedback has been recognized as a mediator of empathy and prosocial behavior.
Finally, it should be noted that certain facial expressions require effort to be maintained, which may influence the experienced fluency in information processing. The experience of fluency was found to serve as a basis for other feelings and judgments, like those of familiarity and fame. For example, it has been found that judgments of fame are often based on the feeling of familiarity that is elicited by a name. More recently, it was demonstrated that having participants furrow the brow while reading the names reduced the fame that was associated with the names. This was presumably the case because the experienced effort undermined the feelings of familiarity and, as a consequence, the judged fame.
- Laird, J. D. (1974). Self-attribution of emotion: The effects of expressive behavior on the quality of emotional experience. Journal of Personality and Social Psychology, 29, 475-486.
- Strack, F., Martin, L. L., & Stepper, S. (1988). Inhibiting and facilitating conditions of the human smile: A nonobtrusive test of the facial feedback hypothesis. Journal of Personality and Social Psychology, 54, 786-777.
- Zajonc, R. (1989). Feeling and facial efference: Implications of the vascular theory of emotion. Psychological Review, 39, 117-124.