title: A three-dimensional study of facial mimicry in healthy young adults.
abstract: To assess sex-related characteristics in facial movements, and to define a set of reference normal values, 20 healthy young adults (10 men, 10 women) performed six standardized facial movements (maximum smile; free smile; "surprise" with closed mouth; "surprise" with open mouth; right- and left-side eye closures). The three-dimensional coordinates of 21 soft-tissue facial landmarks were recorded by an optoelectronic motion analyzer, their movements computed, and standardized for facial dimensions. Asymmetry indices were calculated. The mouth area had the largest movements. Sex-related differences were found only for the superciliare landmark (men had larger movements than women, p<0.001). Asymmetries in the eyes, mouth and nose were similar in both sexes (p>0.01), with a significant effect of movement (p<0.001): eye and mouth asymmetry was larger during the asymmetric eye closures than during the symmetric movements. The right-side asymmetric movements were somewhat larger than the left-side ones. The total facial movement did not differ between sexes; the "surprise with mouth open" movement had the largest landmark displacements (p<0.001). In conclusion, normal young adult men and women had similar standardized facial movements, except in the forehead. Some individual asymmetry was found in symmetric facial animations; some synkinesis was found even in normal adults.
authors.affiliation: Dipartimento di Morfologia Umana e Scienze Biomediche Città Studi, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy. chiarella.sforza@unimi.it
authors.forename: Chiarella
authors.initials: C
authors.lastname: Sforza
authors.forename: Domenico
authors.initials: D
authors.lastname: Galante
authors.forename: Yuri F
authors.initials: YF
authors.lastname: Shirai
authors.forename: Virgilio F
authors.initials: VF
authors.lastname: Ferrario
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002508:Cephalometry / Q000379:methods*; D005145:Face / Q000033:anatomy & histology; D005146:Facial Asymmetry / Q000175:diagnosis; D005149:Facial Expression; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012727:Sex Characteristics; D055815:Young Adult