ABSTRACT
Is it possible to improve your mood, just by smiling? Research into the facial feedback hypothesis indicates that there may be some credence to the old adage of “grin and bear it.” Originally sparked by Charles Darwin in his book, The expression of the emotions in man and animals, in 1872, the concept of physiological changes having an impact on the experience of emotions had been addressed by researchers looking for confirmation ever since. There have been a myriad of researchers who have addressed the facial feedback hypothesis from many angles.
There are many contributors involved in the expression of an emotion, supplied from external stimuli, internal states, and even culture. While the exact neurological reason behind the impact outward expression has on emotional experience is still unclear, the psychological effects are evident.
THEORIES AND RESEARCH ON THE FACIAL FEEDBACK HYPOTHESIS
The facial feedback hypothesis is the thought that facial movement can influence emotional experience. In a well documented experiment, participants were asked to hold a pen in their mouth, either between their lips or with their teeth, then asked to rate the humor of a cartoon (Strack, Martin, & Stepper, 1988). Holding the pen between their lips, the participants contracted the
orbicularis oris muscle, resulting in a frown, and were unable to contract the zygomatic major muscle involved in smiling. However, those who held the pen between their teeth were able to contract this muscle and forced them to smile. The results indicated that the participants who smiled while holding the pen in their teeth, were more likely to rate the cartoon as more funny. This is quite an amazing discovery, considering the cartoon was the same in each condition, with the only difference lying in the contracting of the zygomatic major muscle.
The muscle contracted during the mouth pen holding experiment, the zygomatic major muscle, which causes the cheek muscles to draw lip corners up toward the cheekbones, is the same one that is associated with the Duchenne, or genuine smile. This type of smile is usually thought of a more felt smile and also involves activation of the orbicularis oculi, or the muscle of the eye that causes the “crow’s feet” in the corners of the eye. It is hypothesized that an individual experiences greater pleasure when displaying a genuine, Duchenne smile when compared to a non-Duchenne smile, which supports the facial feedback hypothesis (Surakka & Hietanen, 1998).
Another, more recent study, involved participant evaluation ratings regarding the pleasantness of pictures, composed of neutral faces or nature scenes (trees, forests, and landscapes). The two experimental conditions in this study required the participants to look at the pictures while either elevating their cheeks (similar to a smile), or contracting their eyebrows (associated with frowning). As with the Strack study, the results confirmed the facial feedback hypothesis, since the participants who were in the smiling group rated the pictures as more pleasant when compared to the frowning group (Dimberg & Söderkvist, 2010).
While there appears to be a plethora of research supporting the facial feedback hypothesis, there have been some opponents who have voiced their own opinions. One of the first to suggest an alternative to the facial feedback hypothesis was William James who posited in 1884 that instead of a change in the muscles and facial expression producing the emotion, the emotion leads to the changes. James proposed four steps in the generation of subjective experience of an emotion, which consist of: a sensory stimulus transmitted to the cortex and perceived; the reflex impulses travel to muscle and skin; the changes in these areas are transmitted back to the brain; the return impulses are perceived, and when combines with the original stimulus perception, produce the “object-emotionally-felt” effect (James, 1890). James’ theory of emotion is similar to the facial feedback hypothesis, but in reverse, starting with the appraisal of the stimuli which leads to a change in the facial muscles, followed by an assessment by the brain, producing the emotional experience.
The Differential Emotions Theory, developed by Carroll Izard in 1971, suggested that the primary components of emotion include neural activity, striate muscle, and subjective experience of the individual.
Izard suggested that each emotion operates as a system of interacting neural, expressive, and experiential components, and upon cognition occurring, the emotion is expressed. According to the differential emotions theory, emotions retain their adaptive and motivational functions, which aid in social interactions (Abe & Izard, 1999).
Another theory that arose in the light of the facial feedback hypothesis was that of the self-attribution theory of emotion, which suggests that emotions are a mixture of autonomic arousal and cognitive processing (Schachter, 1964). The interesting part of the self-attribution theory is that the reaction to the emotion being experienced is able to be
operationalized, therefore, less subjective, and possibly more reliable than the results gathered during self-reports from participants.
In 1980, Ross Buck suggested that there may be two different renderings of the facial feedback hypothesis, the between-subjects and the within-subjects versions. The between-subjects design suggests that individual differences contribute to the experience of emotions, for example, if one person freely expresses their emotions, they will have a greater response when compared to someone who shows little expression. Studying of the between-subject version has led to objective supporting evidence, particularly regarding
nonexpressive people. While holding in an emotional expression, it has been noted that there is an increase of heart rate and skin conductance when reacting to a
stimuli. This finding may suggest that facial feedback is not necessary for the experience of an emotion to occur. The within-subject aspect of Buck’s theory holds that when the free
expressor is experiencing a given emotion, if they outwardly express rather than stifle the emotion, they will have a greater external response and the emotion will increase in intensity.
Building on Buck’s within-subject aspect of the facial feedback hypothesis, the difference between
internalizers and
externalizers needs to be addressed. Individuals in the internalizing group do not freely express emotions, whereas
externalizers freely express what they are feeling and experiencing. According to a somewhat unethical study involving electric shock, those who exaggerated the intensity of the shock were actually experiencing more pain than a group who suppressed their pained expressions while receiving a shock of equal value (Lanzetta, Cartwright-Smith, & Kleck, 1976). This research also revealed that when compared to the baseline, hiding a facial response to the shock also reduced the galvanic skin response (GSR). These findings suggest that when suppressing, or internalizing the reaction to a stimulus, the experience is actually less intense. While the
externalizer-
internalizer distinction doesn’t seem to fit with, and may even contradict the facial feedback hypothesis, they are actually quite similar, since both examine the link between the external expression and the internal experience of emotions.
COGNITIVE LINK BETWEEN THE INTERNAL AND EXTERNAL
There is a complex network of nerves, muscles, and brain functions associated with the expression of an emotion that lies beneath the skin. Although it has not been empirically shown, research has speculated that the feedback from the muscles of the face and skin during genuine and imitation expressions is sent to the amygdala and the neural network, where it leads to the experience of the expressed emotion (Hennenlotter, Dresel, Castrop, Cebellos-Baumann, Wohlschläger, & Haslinger, 2009). The amygdala is a key component in the processing of emotions, and has been considered “the gateway to the emotions” (Aggleton & Mishkin, 1986). Some of the roles of the amygdala include evaluating if a stimulus is dangerous or harmless, pleasant or unpleasant, and is a major contributor to the facial expressions of emotions, both intentional and unintentional (Habel, Windischberger, Derntl, Robinson, Kryspin-Exner, Gur, & Moser, 2007).
In order to research the role of the amygdala in the processing of emotions, researchers used functional magnetic resonance imaging (
fMRI) to monitor activity in the brain when exposing participants to pictures of five basic emotions (happiness, sadness, anger, fear, and disgust) along with neutral faces. Participants were also asked to provide an approximate age for the person that was displaying the emotion. Results show that when participants attempt to identify which emotion they are seeing, there is
activation in the amygdala in both conditions (emotions and age); however, there was far greater activity present when trying to identify the emotion. This suggests that the amygdala plays a large role in the identification of emotions, as well as appraisal of the emotions viewed (Habel et al., 2007). It has also been noted that when processing a fearful expression, activity in the orbitofrontal cortex also occurs (Neta & Whalen, 2010).
INTERNALIZERS AND EXTERNALIZERS
As mentioned earlier in Buck’s within-subject version of the facial feedback hypothesis, there are two different kinds of individuals, those that freely express their emotions,
externalizers, and those that stifle their expressions,
internalizers. Personal differences between
internalizers and
externalizers may also dictate which category a person may fall into. Previous research has suggested that females are more facially expressive than males in emotion-provoking situations.
In a study conducted by Thurnberg and Dimberg (2000), researchers set out to determine whether females were generally more facially reactive, or if they were more emotionally reactive in general, compared to men. Participants were deceived as to what the exact nature of the experiment was, in order to prevent bias or demand characteristics. Two groups, composed of either male of female participants, were exposed to fear-relevant and fear-irrelevant stimuli while an
electromyography machine monitored the activity from the corrugator supercilii muscle region (activity in this region is associated with the exhibition of the fear expression, which consists of the eyebrows being raised, opening the eyes widely).
In order to effectively induce a fear response in the participants, researchers used pictures of snakes, which has been shown to reliably produce an increase in
corrugator muscle activity, and are usually consistently rated as being unpleasant. Participants were also exposed to fear-irrelevant stimuli (flowers), which have been shown to induce either a neutral of slightly positive facial reaction (Dimberg, 1997), in order to determine if the changes in activity were due to the individual or the stimuli. After exposure to each set of pictures, fear-relevant (snakes) and fear-irrelevant, the participants were asked to rate how unpleasant they experienced the stimuli.
When evaluating the results of the corrugator muscle activity, there was not a significant difference when comparing the fear-relevant and fear-irrelevant stimuli; however, there was a difference in the activity level between the two groups. It was discovered that females not only produced a larger response than males to the fear-relevant stimuli (snake pictures), but the responses of the females differed between both stimuli as well; females showed a larger
corrugator response to the fear-relevant than the fear-irrelevant stimuli. In this experiment, the
participants in the male group would be considered
internalizers and the participants in the female group would be considered
externalizers, since there was more
corrugator muscle activity in response to the fear-stimuli.
Researchers have suggested many reasons as to why this difference between males and females exist, including
genetics differences in the central nervous system, cultural influences that have worked to inhibit the fear expression in males (Brody & Hall, 1993), and even a possibility that females are more perceptually sensitive than males (Buck, 1984). Females may also have a genetically evolved fear response that has developed out of necessity for protection of offspring in dangerous situations.
Many studies have supported the hypothesis of increased facial
expressiveness of emotion is correlated with increased physiological arousal. In a study involving exposing participants to pictures of people exhibiting happiness, sadness, anger, or fear, while monitoring blood pressure and heart rate, researchers discovered that there was a
measureable correlation between the stimuli photos and the physiological reactions. Fear and happiness
were linked with and increased heart rate, however, in the
fear condition, the heart rate increased more (Schwartz et al., 1981). This increase in heart rate as a response to fear may be an example of the fight-or-flight response that has evolved in order to keep a species alive and able to escape danger.
The increase in emotional expression among
externalizers has been thought of as a form of cathartic discharge, since according to some, emotion must find an exit, and if it cannot be vented outwardly through expression, it is routed inward, resulting in physiological changes. According to Jones (1948), individuals who outwardly express emotion but show little arousal, or physiological changes, are
externalizers; whereas those who show little to no outward emotion, but substantial autonomic physiological activity are
internalizers.
When studying the physiological differences between
internalizers and
externalizers, the results are mixed. Research involving voluntary facial expressions of anger, disgust, neutral, and control conditions during anger imagery showed that the voluntary facial anger reduced blood flow volume, but did not show an increase in heart rate, contrary to the findings of Schwartz et al.
in the previous study (Ianni, Stettner, & Freedman, 1986).
It is suggested by researchers Boden and Dale, that
internalizers are individuals who habitually and effectively control their emotions and that there are immediate and significant consequences
to such regulation. While devoting tremendous energy to prevent externalizing behavior from surfacing, there may be not only
higher blood pressure and pulse present, but also possibly a diminished memory and cognitive processes (Boden & Baumeister, 1997). It appears that
internalizers may have a way of protecting themselves from unpleasant events, possibly by generating pleasant thoughts; they are able to avoid processing of unpleasant emotions.
WHAT HAPPENS WHEN THE FACIAL FEEDBACK PATHWAY IS BLOCKED?
In a quest to maintain a youthful appearance, many women, and some men, have turned to injections of botulinum toxin, or Botox, to prevent the appearance of wrinkles. Botox, a deadly poison, causes temporary muscle paralysis by preventing acetylcholine release at the neuromuscular junction, acting as a roadblock to expression formation (Dastoor, Misch, & Wang, 2007). Patients are advised that Botox will not keep them from expressing themselves, just their facial expressions. Some of the more popular areas for injection of Botox includes the glabellar rhytides (involved in furrowing of the brow), horizontal forehead lines, and crow’s feet, all areas involved in routine facial expressions (Alam, Barrett, Hodapp, & Arndt, 2007). With these locations being paralyzed, would the inhibition of facial expressions lead to an interrupted facial feedback pathway? Since the theory of the facial feedback hypothesis suggests that posing a facial expression should increase the intensity of the emotional experience, inhibiting the facial expression should decrease it.
Research into how Botox affects emotional experience suggests that when the facial feedback pathway is blocked, the strength of the emotional experience is decreased. One study compared self-reports of emotional experience of participants before and after they received one of two types of cosmetic facial injections, either Botox or Restylane (Davis, Senghas, Brandt, & Ochsner). Unlike Botox, Restylane acts as a filler and does not cause temporary muscle paralysis. In order to evaluate any changes between the pre and post injection responses, emotional response to positive and negative video clips were recorded. Upon analyzing the within-group results, there were no statistically significant findings, however, when comparing the between-group data, the participants who received Botox injections showed a significant decrease in the strength of emotional experience. These results suggest that when the facial feedback pathway is inhibited, there is indeed a diminished experience of emotion, confirming the facial feedback hypothesis.
By paralyzing the target muscles, specifically the orbicularis oculi, less Duchenne-type smiles may occur, however, it may also result in a more positive mood. By reducing the furrowing of the brow associated with negative emotional expressions, it may lead to a more positive emotional expression (Alam et al.).
According to the facial feedback hypothesis, expressing more positive emotions may lead to more smiling and a happier emotion, however, on the other side, by losing the ability to display negative emotions, the expressions of disgust, fear, and anger may be diminished. With the possibility of losing the ability to express emotions, physicians who perform Botox injections are urged to consult with their patients, especially those who rely on demonstrative facial expressions (actors, salespersons, teachers), a side effect
to injections may include distress due to the inability to effectively transmit their emotions (Singh, 2003).
CLINICAL APPLICATIONS
If our emotional states are a result of our facial expressions, it would be presumed that by smiling, individuals who are depressed could improve their mood. Impairment in the ability to smile may elevate the risk for depression, since according to the facial feedback hypothesis, if an emotion is not able to be expressed, that emotion will not be fully experienced (VanSwearingen, Cohn, & Bajaj-Luthra, 1999). In addition to not being able to experience the emotion, another side effect to an inability to smile is that some may experience increased social isolation due to their impaired ability to communicate positive emotion in social contexts (Fridlund, 1991). In a different study of individuals with depression, researchers discovered a positive correlation between patients with a higher level of EMG activity measurements of the
corrugator and
zygomatic face muscles and more positive treatment outcomes (Greden, Price, Genero, Feinberg, & Levine).
In studies involving individuals without smile impairment, some research has supported that facial expressions can influence emotions. In an experiment, participants experienced increased positive moods when they engaged in positive facial expressions and decreased positive moods when they engaged in negative facial expressions (Kleinke, Peterson, & Rutledge, 1998).
Since, according to the facial feedback hypothesis, we are able to deliberately control and change our feelings and emotions, we are also able to control the physiological responses associated with them. This idea would be quite useful in a clinical setting, and has been employed in many relaxation-based therapeutic practices. It is suggested that relaxing facial and other muscles may produce a positive experience of relaxation, while reducing muscle tension and negative emotions (Duclos & Laird, 2001).
CONCLUSION
The debate over the facial feedback hypothesis, which was started over 200 years ago, is far from being over. As with any good scientific method, researchers will continue to try to find supporting evidence as well as contrary evidence regarding how, and if, facial expressions do indeed have an impact on the emotional experience. Some of the debate regards the inner workings of the brain and how it relays information; others are concerned primarily about the objectivity involved in the collection of data. No matter which side of the hypothesis you may find yourself, you will find controversy, which is a sign of progress.
**References available upon request**
