Can Duchenne smiles be feigned? New evidence on felt and false smiles.

We investigated the value of the Duchenne (D) smile as a spontaneous sign of felt enjoyment. Participants either smiled spontaneously in response to amusing material (spontaneous condition) or were instructed to pose a smile (deliberate condition). Similar amounts of D and non-Duchenne (ND) smiles were observed in these 2 conditions (Experiment 1). When subsets of these smiles were presented to other participants, they generally rated spontaneous and deliberate D and ND smiles differently. Moreover, they distinguished between D smiles of varying intensity within the spontaneous condition (Experiment 2). Such a differentiation was also made when seeing the upper or lower face only (Experiment 3), but was impaired for static compared with dynamic displays (Experiment 4). The predictive value of the D smile in these judgment studies was limited compared with other features such as asymmetry, apex duration, and nonpositive facial actions, and was only significant for ratings of the upper face and static displays. These findings raise doubts about the reliability and validity of the D smile and question the usefulness of facial descriptions in identifying true feelings of enjoyment.