Smiling By Way of Zygomatic Electrical Stimulation: Investigating the Facial Feedback Hypothesis

While it is widely accepted that affective states precede facial expressions, the facial feedback hypothesis (FFH) proposes the inverse. The FFH postulates that facial muscle region activity (e.g., smiling or frowning) directly influences the experience of emotion. The purpose of the present study was to evaluate the validity of the FFH - specifically whether smiling independently enhances positive mood.

Demand characteristics moderate, but do not fully account for, the effects of facial feedback on emotional experience

The facial feedback hypothesis suggests that an individual’s facial expressions can influence their emotional experience (e.g., that smiling can make one feel happier). However, a reoccurring concern is that demand characteristics drive this effect. Across three experiments (n = 250, 192, 131), university students in the United States and Kenya posed happy, angry, and neutral expressions and self-reported their emotions following a demand characteristics manipulation. To manipulate demand characteristics we either (a) told participants we hypothesized their poses would influence their emotions, (b) told participants we hypothesized their poses would not influence their emotions, or (c) did not tell participants a hypothesis. Results indicated that demand characteristics moderated the effects of facial poses on self-reported emotion. However, facial poses still influenced self-reported emotion when participants were told we hypothesized their poses would not influence emotion. These results indicate that facial feedback effects are not solely an artifact of demand characteristics.

A Multi-Lab Test of the Facial Feedback Hypothesis by The Many Smiles Collaboration

The facial feedback hypothesis suggests that an individual’s subjective experience of emotion is influenced by their facial expressions. Researchers, however, currently face conflicting narratives about whether this hypothesis is valid. A large replication effort consistently failed to replicate a seminal demonstration of the facial feedback hypothesis, but meta-analysis suggests the effect is real. To address this uncertainty, a large team of researchers—some advocates of the facial feedback hypothesis, some critics, and some without strong belief—collaborated to specify the best ways to test this hypothesis. Two pilot tests suggested that smiling could both magnify ongoing feelings of happiness and initiate feelings of happiness in otherwise non-emotional scenarios. Next, multiple research sites will perform more extensive tests to examine whether there is a replicable facial feedback effect.

A Meta-Analysis of the Facial Feedback Literature: Effects of Facial Feedback on Emotional Experience Are Small and Variable

The facial feedback hypothesis suggests that an individual’s experience of emotion is influenced by feedback from their facial movements. To evaluate the cumulative evidence for this hypothesis, we conducted a meta-analysis on 286 effect sizes derived from 138 studies that manipulated facial feedback and collected emotion self-reports. Using random effects meta-regression with robust variance estimates, we found that the overall effect of facial feedback was significant, but small. Results also indicated that feedback effects are stronger in some circumstances than others. We examined 12 potential moderators, and three were associated with differences in effect sizes. 1. Type of emotional outcome: Facial feedback influenced emotional experience (e.g., reported amusement) and, to a greater degree, affective judgments of a stimulus (e.g., the objective funniness of a cartoon). Three publication bias detection methods did not reveal evidence of publication bias in studies examining the effects of facial feedback on emotional experience, but all three methods revealed evidence of publication bias in studies examining affective judgments. 2. Presence of emotional stimuli: Facial feedback effects on emotional experience were larger in the absence of emotionally evocative stimuli (e.g., cartoons). 3. Type of stimuli: When participants were presented with emotionally evocative stimuli, facial feedback effects were larger in the presence of some types of stimuli (e.g., emotional sentences) than others (e.g., pictures). The available evidence supports the facial feedback hypothesis’ central claim that facial feedback influences emotional experience, although these effects tend to be small and heterogeneous.

Bodily Feelings Emerge in the Insular Cortex

This chapter presents evidence that supports the idea that activity in the interoceptive cortex in the posterior insula is re-represented, integrated, and transformed in the middle and anterior portions of human insular cortex to generate the feelings that one experiences. It also explains how vivid feelings are generated in a model of interoceptive integration that engenders homeostatic sentience. The emergence of bodily feelings provides the foundation for the generation of emotional feelings in the anterior insular cortex as if they are feelings from the body. The chapter then describes the evidence for the embodiment of emotional feelings, including the recent use of Botox to elucidate central mechanisms for the facial feedback hypothesis.