The expression “a smile a day keeps the blues away” may have some credence beyond the realm of greeting card messages. The lingering question of whether a smile or frown lifts or depresses emotion has persisted for decades and is still actively debated.
…
The idea that the body plays a role in shaping how people feel and perceive the world is “old and fascinating,” says Sebastian Korb, a senior lecturer in psychology at the University of Essex in England and senior author of the research, which was published in Emotion. “But it’s not universally accepted.” Korb says that the new study suggests that facial activity does seem to influence emotions and adds evidence to this long-standing but contentious hypothesis.
…
Heather Lench, a professor of psychological and brain sciences at Texas A&M University, who was not involved in the research, says the new study was done well and “opens up a new way to induce facial expressions.”