Can Smiling Make You Happier? The Intriguing Power Of The Facial Feedback Hypothesis

The facial feedback hypothesis suggests that our facial expressions can shape our emotions, not just reflect them, so smiling may make you feel a little happier and frowning a little sadder. The effect is real but small and variable: large multi-lab studies find smiling gives mood a modest lift rather than a guaranteed cure for sadness.

Have you ever felt low and Googled ways to feel happier? While it may seem counterintuitive, the facial feedback hypothesis suggests that simply smiling can nudge your mood upward. In other words, it’s not just our emotions that shape our expressions… our expressions can also shape our emotions!

The Facial Feedback Hypothesis

Intuitively, we believe that emotions dictate our expressions. If we’re happy, we smile; if we’re sad, we frown; if we’re annoyed, we scowl. However, the facial feedback hypothesis challenges this one-way street. It suggests that our expressions can also influence our emotions. So, when you’re feeling sad, smiling can alter your mental frown and possibly flip it upside down!

How do we know this?

In 1988, psychologist Fritz Strack and colleagues conducted a now-famous study to test the hypothesis. In their experiment, participants were made to rate the humor of cartoons while holding a pen in their mouths, either with their lips or with their teeth. This effectively forced them to either maintain a neutral expression or mimic a smile, respectively.

Participants who held the pen with their teeth, mimicking a smile, found the cartoons significantly funnier than those who held the pen with their lips, thus maintaining a neutral expression.

That tidy result became a textbook classic, but the story didn’t end there. In 2016, 17 labs around the world joined a Registered Replication Report to repeat the pen study under tightly controlled conditions. They couldn’t reproduce it: the original reported a difference of about 0.8 points on a 10-point funniness scale, while the combined replication found a difference of roughly 0.03 points, statistically indistinguishable from zero. The failure became one of the most cited examples in psychology’s “replication crisis,” and it sent researchers back to ask whether the facial feedback effect was real at all.

More recent evidence comes from a study conducted in 2010 by psychologists at Columbia University. These researchers used a unique approach. Instead of a pen to activate facial muscles, the researchers used Botox injections. Before they were given injections, the participants were shown a series of positive and negative videos. The participants were asked to rate their feelings on a scale that ranged from very negative to very positive. After this assessment, one group received Botox injections, which paralyze the facial muscles, limiting the muscles’ movement. The other group, the control group, received Restylane, a drug that only fills in wrinkles and does not affect muscle movements.

Between 14 to 24 days after the injections, the participants were once again shown positive and negative video clips (different ones, this time). After that, they were again asked to rate their emotional responses. The group that received Botox injections reported weaker emotional reactions to both types of video clips, as compared to the first time they had seen them. In other words, they experienced reduced negative emotions after viewing the negative clips and diminished positive emotions after viewing the positive ones.

So is the effect real or not? To find out, researchers stopped relying on any single experiment and pooled the whole literature. A 2019 meta-analysis published in Psychological Bulletin combined 138 studies and more than 11,000 participants. It found that facial feedback does influence emotion, but the effect is small and variable. In plain terms: adopting a positive expression like a smile can nudge your mood in a positive direction, but the size of that nudge depends heavily on the situation and the method used.

The strongest evidence yet comes from a 2022 multi-lab study, the Many Smiles Collaboration, published in Nature Human Behaviour. Across 26 labs and nearly 3,900 participants in 19 countries, deliberately posing a smile (or mimicking one from a photo) produced a small but reliable boost in reported happiness. Tellingly, the older pen-in-mouth trick was the least convincing method, which helps explain why the 1988 study had been so hard to replicate.

All of this tells us that the facial feedback hypothesis is real but modest: smiling can lift your mood a little, not flip a switch from sad to happy.

Why Does This Happen?

The facial feedback hypothesis operates through a feedback loop, where the physical act of smiling triggers positive emotions. This, in turn, reinforces the act of smiling.

The honest answer is that scientists don’t fully agree yet, and the popular explanation deserves a caveat. You’ll often read that smiling floods the brain with feel-good chemicals like endorphins and dopamine. The reality is more cautious. Research on the biology of happiness shows that endorphins (the brain’s natural painkillers) are released by activities such as laughter, exercise, and music, and that positive mood is associated with higher dopamine levels rather than directly caused by a smile.

So a more accurate way to put it: a genuine smile, especially one tied to laughter or pleasant activity, can engage the same reward and mood systems that involve dopamine and endorphins. Dopamine is linked to reward and motivation, while endorphins ease stress and pain, both of which can leave you feeling better. The act of arranging your face into a smile may give that loop a small head start.

One thing to remember is that the relationship between smiling, endorphins, and dopamine is a complex area of research. There may be variations or relationships that are yet to be fully understood. The specific mechanisms and the extent to which smiling directly influences endorphin and dopamine release may be different among individuals and definitely requires further investigation.

Engaging In Activities That Disrupt Negative Emotions

Buddhist monk Thích Nhất Hạnh, often called the “father of mindfulness,” put it this way: “Sometimes your joy is the source of your smile, but sometimes your smile can be the source of your joy.”

There are ways to put the facial feedback hypothesis to the test. One way is by doing activities that are directly opposite to what you’re feeling. For example, listening to your favorite upbeat songs or watching a comedy show can introduce elements of joy and laughter into your environment. These actions, though seemingly trivial, can send signals to your brain, helping you feel better. When you listen to your favorite songs or watch a comedy show, your brain receives a signal that things may not be that bad, since you are apparently comfortable and smiling! Smiling shifts your emotional state and creates an opportunity for positive emotions to take over.

Obviously, human emotions are complex, and simply smiling won’t magically cure you of what is hurting. Our nature is influenced by several factors, and it is essential for us to address and process our emotions. Plastering a smile on your face may not always work, or be necessarily healthy, but as a quick fix and a fascinating test of our mental flexibility, try letting your expressions determine your emotions for a while!