In the unspoken language of love, the face you make at the pinnacle of pleasure may have something of an accent based on where you come from.

People from Western and East Asian cultures had consistently different ideas of what facial expressions indicate the moment of orgasm, researchers found in a study published Monday in PNAS. Specifically, Western participants expected widened eyes and gaping mouths, while East Asian participant’s ideas culminated in a slight, tight-lipped smile.

But contrary to those cultural climaxes, the look of dire pain had universal contortions. Participants from both cultures recognized the apex of anguish by inward-pulling facial expressions, such as lowered brows, wrinkled noses, and raised cheeks.

The researchers behind the study—led by psychologists at the University of Glasgow in Scotland—argue that the new data disputes earlier conclusions that faces of physical pain and sexual pleasure are indistinguishable. “This finding is counterintuitive, because facial expressions are widely considered to be a powerful tool for human social communication and interaction,” they note.

With their data coming to a head with different facial expressions, they speculate that culture-specific expectations of o-faces and p-faces could one day be useful to study human interactions. Those nuanced expression could offer an intimate peek into our “complex social world and provide a richer, more accurate account of social communication.”

Racy ratings

To bang out accurate representations of orgasmic and pained facial expressions, the researchers turned to mathematic modeling. They set up a dynamic face-movement generator which randomly selected a set of nuanced facial movements from a core set of 42. Those core movements included things like a mouth stretch, eyelid raising, and jaw dropping. The researchers then displayed those random sets (including one to four facial movements) onto a photorealistic face to produce quickie animations.

The researchers then had 40 participants from each of the two cultures (80 total) look through 3,600 of those animations each. The participants labeled every one of the animations as showing either “pain,” “orgasm,” or “other.” They then ranked the animation's intensity from “very weak” to “very strong.”

From there, the researchers mashed the results within the two cultural groups and let loose assembled facial models for orgasm and pained faces. They had 104 other participants (26 people of both sexes from each of the two cultures) look though them. For this group, the models were each displayed on photorealistic faces of the same race as the participant but the opposite sex. The observers had to discriminate if they thought the face represented pain or orgasm and how well it did at either. The modeled representations were effective, the researchers found: the participants were in consistent agreement about what looked like pain and what looked like pleasure.

With the participant-confirmed representations of o- and p- faces, the researchers then compared how they differed—or didn’t. They found that the pained models had similar inward-pulling facial expressions, while the pleasure models were more culture-specific.

The authors speculate that those differences could be explained by culture-specific expectations and preferences for overt excitement and content calm. More specifically, they explain:

These cultural differences correspond to current theories of ideal affect that propose that Westerners value high arousal-positive states such as excitement and enthusiasm, which are often associated with wide-open eye and mouth movements, whereas East Asians tend to value low arousal-positive states, which are often associated with closed-mouth smiles.

They’ll need more data to back up that hypothesis and confirm their results. But, they add, with new technologies decoding facial movements, such data should be easier to come by in the future.

PNAS, 2018. DOI: 10.1073/pnas.1807862115 (About DOIs).