Children's and Adults' Knowledge of the Distinction Between Enjoyment and Nonenjoyment Smiles

Children's and adults' knowledge of the distinction between enjoyment and nonenjoyment smiles was investigated by presenting participants with short video excerpts of smiles prepared in accordance with the Facial Action Coding System (Ekman & Friesen, 1978). Enjoyment smiles differed from nonenjoyment smiles by greater symmetry and by appearance changes in the eye region produced by the orbicularis oculi action. The results indicate that 9- and 10-year-old children and adults were sensitive to the appearance changes produced in the eye region, but only when they could view the complete temporal dynamic of the smiles. No evidence of sensitivity was found for the level of asymmetry of the smiles, and no evidence of sensitivity for either of the markers was found in 6- and 7-year-old children.