What is a “Duchenne smile?” It is not a smile that just involves the corners of your mouth turning up. Instead, it is a smile that activates both the muscles around the mouth as well as the muscles around the eyes. In all persuasive situations, we are told that a sincere smile can often help. As I’ve shared previously, a smile makes a speaker more credible, and (for reasons that are probably unfair) is especially important for female communicators. Smiling also makes the smiler feel more positive and improves mental outlook. No, that doesn’t mean that you should grin your way through trial, but it does mean that at appropriate moments, a sincere smile can help to convey your warmth and your humanity. The courtroom, of course, is a setting where sincerity matters a lot, and the perceived sincerity of the smile is mostly determined by whether that smile is a Duchenne smile or not.
The alternative, of course, is the non-Duchenne or mouth-only smile. This is also called the "Pan Am smile" (after the defunct airlines who started the practice of having flight attendants give the perfunctory "Thanks for flying..." smile as you exit the plane, and more recently the "Botox smile" in honor of those whose paralyzed muscles around the eyes and forehead cannot participate in the smile. Research in a variety of settings shows the advantage of a full-face smile involving your mouth as well as the crinkles around your eyes. When advertisements use Duchenne smiles as opposed to neutral faces or non-Duchenne smiles, for example, viewers have a significantly better perception of both the ads as well as the product being advertised (Scanlon & Polange, 2011). When tested, only a minority of us can deliberately imitate a Duchenne smile. The rest, when asked to imitate a smile will give a fake smile (Gunnery, Hall & Ruben, 2013). However, with a little bit of attention, we can also learn to give a Duchenne smile whenever we want to (Thibault, Levesque, Gosselin, & Hess, 2012), and those with the ability to produce that Duchenne smile on command end up being more persuasive in interpersonal interactions (Gunnery & Hall, 2014). All of this adds to a body of research showing that Duchenne smiles are more likely to evoke a positive mood from viewer, triggering positive emotional response.