Duchenne smiles and the perception of generosity and sociability in faces

Although Duchenne smiles have been shown to have a social signal value, there is limited evidence as to whether this effect generalises to most positive attributes, or whether it is restricted to a particular social domain. As opposed to non-Duchenne smiles, Duchenne smiles involve the activity of facial muscles in the eye region (orbicularis oculi). The hypothesis that Duchenne and non-Duchenne smiles produce different responses in receivers was tested in a face perception experiment. People were asked to rate neutral and smiling faces on ten attributes: attractiveness, generosity, trustworthiness, competitiveness, health, agreeableness, conscientiousness, extroversion, neuroticism, and openness to experience. Results showed that the type of smile had a stronger impact on the ratings of generosity and extroversion. The difference between neutral and smiling was larger when faces showed a Duchenne than a non-Duchenne smile, though the effect of smile type on attributions of generosity appeared to be restricted to male faces. Therefore the Duchenne marker shows some specificity to judgements of altruism and sociability.