Gladwell's Blink summarizes the work of Paul Ekman and Wallace Friesen and their Facial Action Coding System -- a 500 page catalog of muscle movements that signify emotional states. He also recounts the story of how, in compiling this compendium, they were forced to make a lot of expression of anger and distress.

"It was weeks before one of us finally admitted feeling terrible after one of those sessions," Friesen says. "Then the other realized that he'd been feeling poorly, too, so we began to keep track." (p206)

Hooked up to monitors, they found that pursing the lips, narrowing eyelids, and lowering brows is enough to generate an autonomic response similar to anger. The heart rate rises, the extremities get hot. And the subject feels something.

When studied further, psychologists found that viewers forced into a smile enjoyed comedy more than viewers physicially prevented from smiling. I'm not sure if it's relevant, but the study was German. Also, the smiles were generated by clenching a pen between the subject's teeth (and smiles were prevented by gripping a pen with the lips).

I bring this up in the context of Moebius Syndrome, though it's easily relevant in Parkinson's patients or stroke victims, or general old age.

Moebius Syndrome is sad and interesting: the patients are born with facial nerve paralysis. They can crudely chew and phonate (mediated by other cranial nerves) but can't smile or frown or otherwise express emotion. Patients report frustration at not being able to smile at a friend's joke.

A muscle transplant (gracilis to masseter) lets patients retract the corners of their mouth when they send the impulse to clench their jaw. In addition to improving speech, a rudimentary smile is made possible, on command.

I wonder: does it become natural to clench when a Moebius patient wants to smile? Does it become second nature? Obviously such patients would get more out of human interactions, but, say, if I were a German psychologist, would I find that they suddenly enjoyed watching comedies more?