The following studies are samples from the Facial Feedback literature review by Katherine Wright and published in 2022 in the Undergraduate Research Journal of the University of Utah. To learn more about the following studies (including statistics) and additional Facial Feedback research, read the full Facial Feedback literature review.
Autonomic Nervous System Activity Distinguishes Emotions
Paul Ekman and Wallace Friesen (1978) developed the Facial Activation Coding System (FACS) in the 1970s to assist researchers in identifying the emotional expression of study subjects. They identified 46 action units that comprise common facial expressions and created a manual so others can identify the emotions of subjects in photographs, films, and live research. Ekman and Friesen both experienced strong physical sensations while contracting their facial muscles into facial expressions during the development of the FACS. This experience led them to develop the theory that “voluntary production of emotional facial configurations would produce emotion-specific patterns of autonomic activity” (Levenson et al. 1990).
A few years later, Ekman, Levenson, and Friesen (1983) studied the autonomic responses of six universal emotions: surprise, disgust, sadness, anger, fear, and happiness. The researchers hypothesized that they would find differences in the autonomic responses between the six emotions. Sixteen subjects contracted specific muscles resulting in a prototypical emotional expression and sensations of the emotion. The subjects also “relived” a personal experience relating to a specific emotion. Heart rate, skin temperature, sweating, and forearm muscle tension of the subjects were measured during these tasks.
Ekman, Levenson, and Friesen found a significant increase in heart rate for anger, fear, and sad emotional experiences, but only anger showed a significant difference in skin temperature. Surprisingly, the autonomic responses created by facial expressions were stronger than those created by relived experiences, and support the sufficiency hypothesis that facial expressions, by themselves, can instigate an emotional experience.
Inhibited or Facilitated Smiles
Strack, Martin, and Stepper’s (1988) facial feedback research also supported the sufficiency hypothesis. Ninety-two study subjects were told that injured or disabled people may need to hold a pen in a non-standard way, so the study subjects held a pen in three different ways as they performed simple tasks, including rating the humor of cartoons:
- with lips only (inhibiting a smile)
- with teeth only (facilitating smile)
- with their non-dominant hand—(Figure 2).
The researchers discovered that subjects that viewed the cartoons with the teeth only (which facilitated a smile) rated the cartoons significantly funnier than those who held the pen with lips only (which inhibited a smile) or with the non-dominant hand. This FFH research was one of the first to successfully blind the subjects to the actual purpose of the study, which increased confidence in the results.
Eyebrow Placement Implicates Facial Feedback Correlation with Emotion
Michael Lewis (2012) further explored the facial feedback hypothesis in three experiments. In his first experiment, 54 participants were told the research regarded concentration methods as a cover story. The participants were divided into three groups. One group was instructed to raise their eyebrows high, another group to lower their eyebrows, and a third group was told to keep their eyebrows in the middle. All groups took the Irritability-Depression-Anxiety (IDA) questionnaire. Researchers discovered that the eyebrows-down group scored significantly higher on the IDA for depression and anxiety but not for irritability. Lewis suggested that these results support the idea that BTX treatments could reduce depression by suppressing frowning capability.
The cover story from experiment one was used in a second experiment. The facial feedback influence of surprise or disbelief was explored as 24 subjects either raised their eyebrows as high as possible, lowered their eyebrows as low as possible, or held them constant while rating the plausibility of ten statements that they were told were “facts.” Eyebrow placement proved to impact the emotional impact of the experience. Those with raised eyebrows were more surprised by the “facts.”
The third experiment examined whether facial expressions of disgust would impact the evaluation of odors. Thirty-three subjects were told that researchers were examining how facial muscle activity moved smells to different parts of the nasal cavity. Subjects then forced their noses as high as possible, as low as possible (by lowering the lower lip), or by keeping the nose relaxed as they smelled boxes of mostly unpleasant odors, such as “urine,” “farmyard,” and “vomit.” Once again, facial manipulation of the nose impacted the pleasantness ratings of the smells. Subjects that forced their noses high, creating an expression of disgust, rated the odors as more unpleasant than those who held their noses low or relaxed.
Facial Feedback Meta-Analysis and Effect Sizes
Nicholas Coles, Jeff Larsen, and Heather Lench (2019) evaluated the evidence for the facial feedback hypothesis with a meta-analysis of 138 research studies that examined and measured the effect size of the facial feedback. Effect size measures the strength of the relationship between two variables. In this case, the effect size was the impact of the subjects’ mood from the facial manipulation. The authors indicated that the combined effect sizes from the studies they reviewed were small but varied widely.
The authors of this study identified factors that significantly impacted the effect sizes of facial feedback. Larger effect sizes were found for studies that did not include emotional stimulation but relied on manipulated facial muscles. These results suggest that facial musculature movement might have a more significant impact than some emotionally arousing impetus. In addition, facial feedback effect sizes varied depending on the type of stimuli (see graph below). Some stimuli had smaller effect sizes, and some had more significant effect sizes.
The authors concluded that facial feedback could both initiate and modify emotional experiences, and effect size varies based on the emotional stimulation. Studies testing facial feedback using “Imagined Scenarios” showed the most significant response. Imagined scenarios can be similar to the distorted negative cognitions that depressed individuals experience as they “imagine” that their problems are more severe and hopeless than they are.
Questions or comments? We would love to hear from you.
Katherine Wright
References
Coles, N. A., Larsen, J. T., & Lench, H. C. (2019). A meta-analysis of the facial feedback literature: Effects of facial feedback on emotional experience are small and variable. Psychological Bulletin, 145(6), 610–651. https://doi.org/10.1037/bul0000194
Ekman, P., Friesen W.V. (1978). Facial action coding system: A technique for the measurement of facial movement. Palo Alto: Consulting Psychologists Press.
Ekman, P., Levenson, R. W., & Friesen, W. V. (1983). Autonomic Nervous System Activity Distinguishes among Emotions. Science, 221(4616), 1208–1210. https://doi.org/10.1126/science.6612338
Levenson, R.W., Ekman, P., & Friesen, W. V. (1990). Voluntary facial action generates emotion-specific autonomic nervous system activity. Psychophysiology, 27, 363–384. https://doi.org/10.1111/j.1469-8986.1990.tb02330.x
Lewis, M.B. (2012). Exploring the positive and negative implications of facial feedback. Emotion, 12(4), 852–859. https://doi.org/10.1037/a0029275