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EKMAN, PAUL; ROPER, GOWEN; and HAGER, JOSEPH C. Deliberate Facial Movement. CmLD DEVELOPMENT, 1980, 51, 886-891. Children aged 5, 9, and 13 years tried to imitate elemental and complex facial actions. Performance improved with age, and also when the children had the benefits of practice, encouragement, and seeing themselves in a mirror. The ability to imitate elemental actions correlated with the ability to imitate complex expressions. Certain actions, primarily those involved in fear, sadness, and anger, were difficult even for the oldest group. The relationship between making faces by deliberate action and making faces by selfgenerating an emotion experience is discussed.
Ekman et al. (Mon,) studied this question.