Getting a solid scientific answer to the question of whether smiling really makes you feel better has proven to be exceedingly tricky. It’s not just as simple as telling someone to smile and then devising a way to test whether they’re happy or not. You’ve got to figure out whether it’s the physical act of smiling that makes a difference and not, for example, the request that the person smile. And then there’s the question of whether the smile is genuine or not. For that, researchers may be able to turn to the newly developed smile detector, which ranks gleeful visages as percentage scores. (The guy on the left isn’t sure if he wants to be there.)

Cognitive Daily has a very insightful review of the history of smile studies, which demonstrates just how clever scientists have to be sometimes to get to a valid conclusion.—Gregory Mone