Electromyography (EMG)


Certain facial muscles are associated with self- and other-reported emotional responses. For example, pulling one’s cheeks toward one’s ears into a smile is not surprisingly associated with liking and positive emotion. However, many times these muscle reactions are too small to be noticed by observers or felt by participants. Facial electromyography (EMG) allows researchers to measure these minute electrical changes in muscle activation.


In the Langlois Social Development Lab, we have used EMG as a measure of positive emotion, negative emotion, and disgust in response to faces and other objects differing across many different categories. For example, we sought to test whether the stereotypes for attractive and unattractive faces might be associated with physiological changes in emotion. We found that both 7- to 10-year-olds and adults showed less negative affect and disgust to human faces that are rated as attractive compared to those that are rated as unattractive.

We were also interested in testing two theories on the origins of attractiveness preferences, evolution and natural selection, as well as cognitive averaging theory (as described in further detail, here). We exposed adults to pictures of human faces that had been morphed into chimpanzee faces. Although these morphed faces were rated as very unattractive, we found that participants who viewed these photos had a) more positive affect to faces that were morphed with chimps compared to faces that were 100% human and b) more positive affect than participants who viewed human faces only. These results suggest that experience determines facial attractiveness preferences rather than an innate beauty-detecting template.

Currently, we are using EMG to compare people’s emotional reactions to faces versus non-face objects to continue to test whether facial attractiveness provides unique cues compared to objects with which we have much experience.