Our emotions and our expressions are clearly linked. You smile as a reaction to happiness, but did you know that a forced smile can trigger the reverse and make you happier? If you feel blue and then force a smile it can trigger a better mood—the muscle movement activates brain activity associated with happiness. Pouting, likewise, can deepen your funk.As Darwin first suggested, expressing an emotion may intensify it. Later, turn-of-the-century psychologists William James and Carl Lange theorized that physiological responses trigger emotion rather than the other way around, as you might expect.The ‘‘facial feedback hypothesis’’ got a big boost in 1989 from the late Stanford psychologist Robert Zajonc. To test the emotional impact of seemingly neutral movements, he had subjects make the long “e” sound, which stretches the corners of the mouth outward—as if they were smiling. Subjects also made the “long u” which forces the mouth into a pout. As predicted, people said they felt good after making the long “e” sound, and not good after pursing their lips.COLUMN: The Power of Smiles by Art Markman, Ph.D.Psychologists also agree that when we feel connected to others, we subtly imitate their movements. Mimicry begins in infancy: stick out your tongue to a cradled infant and she may well stick out hers, making you swoon with adoration. Put it all together: When a baby smiles because I smile, the smile itself triggers happiness in the baby—and seems to make her like me more. I smile again in return, and we all glow together.These two theories—about facial feedback and mimicry—are the backdrop for the current debate about Botox injections. Last year, nearly 2.5 million Botox injections were reported in the United States, according to the American Society for Aesthetic Plastic Surgery, a 50 percent increase from 2002, when the Food and Drug Administration first approved the procedure for cosmetic purposes.MORE: When Mimicking BackfiresThe treatment typically paralyzes the corrugator muscles between the eyebrows, which can clench into a crease that suggests stress and anger. What happens if we can’t move our facial muscles freely? Are people who get Botox-ed blunting their emotional lives?The answer seems to be…maybe, somewhat. The science is new. While scientists agree that facial feedback intensifies emotion, there’s less evidence that it’s essential. In a 2002 case study of a patient with a completely paralyzed face, for example, even though she couldn’t express her feelings in her face, she reported normal internal experience and was able to identify emotions in others.MORE: Botox Users Perceived to Be Colder, More VainBut recent studies do show measurable effects of Botox on emotions. In one, when subjects consciously imitated angry or sad expressions they saw in photographs, Botox-ed subjects showed less brain scan activity in key regions for emotion than a comparison no-Botox group.In another, patients read statements evoking anger (“The pushy telemarketer won’t let you return to dinner”), sadness (“You open your e-mail inbox on your birthday to find no new e-mails”) or happiness (“The water park is refreshing on the hot summer day.”). Two weeks after receiving a forehead injection of Botox, patients took longer to press a button indicating that they’d understood the angry and sad sentences, suggesting that emotion processing may have been affected. There was no change in how long it took them to understand the happy phrases.Blunted reactions—or a “frozen” look—can potentially chill communication, which trickles down to affect others’ feelings towards the person with Botox. After all, people respond, often unconsciously, to fast, subtle cues. If you can’t fully react as I tell you about an event that made me angry, I might think you aren’t listening or sympathetic to me. “I worked with a girl who had frozen eyebrows,” says a colleague who chose to remain anonymous. “I could never really tell if she got what I was saying because her facial expressions didn’t match her voice and words. It was weird, and I felt like our friendship suffered a little bit because of it.”MORE: Different Cultures Read Facial Expressions DifferentlyIn an extreme example, people with autism spectrum disorders, who have trouble with empathy, tend not to spontaneously mimic expressions.Ordinary, small joys, many say, are the secret of happiness. So it wasn’t good news for Botox fans when the latest study reported that a Botox-ed group showed weaker reactions to mildly happy clips.Researchers at Columbia University treated 68 women, ages 27-60, with typical cosmetic procedures. One group had Botox injected into the frown lines between the eyes and the laugh lines, or “crows feet,” around the eyes. In another, they injected Restylane (a cosmetic filler that does not paralyze muscles) into the folds running below the nose around the sides of the mouth. These rest above portions of a muscle used to raise the upper lip in disgust and another involved in smiling.THIS STUDY, EXPLAINED: Botox Weakens EmotionThe women watched a series of positive and negative video clips, and rated their emotional response before and after treatment.Unexpectedly the Restylane group showed stronger reactions, compared to the Botox-ed group, to clips eliciting disgust. Although Restylane is not known to affect muscles, it does cause swelling, which may have amplified sensation—and stimulated the muscle used to express disgust.Within the Botox-ed group, there was no strong difference in their before-and-after response to the most dramatic clips. The group’s flatter response to the mildly happy clips suggests that the effect of the paralysis may be greatest when the emotion is weak (and most easily influenced by external cues). If so, the effect may be easy to miss.This squares with the experience of plastic surgeons and patients, who report that Botox doesn’t hurt their emotional life or communication. “I have injected Botox into several thousand patients and I have never had a patient tell me that they had any blunting of their emotions,” says Arthur Perry, M.D., YouBeauty Cosmetic Surgery Expert.MORE: Get the Facts on BotoxTo the extent that Botox does dampen negative emotion, could it be helpful for patients who are depressed? One study tested a small sample of only 10 patients who were seriously depressed (in spite of treatment with medication or therapy) and received a Botox injection to their frown lines. Two months later, nine out of 10 appeared no longer depressed in evaluations from doctors and tests using a standard inventory for depression. Davis points out, however, that because “there are likely many different ways that our muscle movements influence our emotions, both directly and indirectly, […] it is hard to predict how paralyzing those muscles would influence emotion in the long term.”My own experience is that wrinkles from age can be misinterpreted—a reason for a cosmetic procedure. Sometimes I’d ask my mother, “Are you okay?” and she’d say, with frustration, “I’m fine, it’s just my face!” The corners of her mouth drooped down, and even though as her daughter I knew her expressions intimately, I tended to sense unhappiness whenever her face came to rest. I notice as I get older that my own mouth is drooping, which has made me consider Restylane.That said, I’d rather not stimulate my disgust muscles. I think I’ll wait for more evidence, either way. As for Botox, the chance of less pleasure from small events like a pleasant exchange with a bus driver seems direr than it sounds—those lost moments could truly add up.QUIZ: How Healthy is Your Skin?