title: A comparison of the reproducibility of verbal and nonverbal facial gestures using three-dimensional motion analysis.
abstract: OBJECTIVE
  To evaluate the reproducibility of selected verbal and nonverbal facial gestures.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  School of Dentistry, Cardiff University, Cardiff, United Kingdom.
  
  
  METHODS
  Twenty-five white subjects were asked to perform four verbal gestures and two nonverbal facial gestures in a normal, relaxed manner. The sequences were captured using a noninvasive, three-dimensional motion analysis scanner (3dMDFace Dynamic System; 3Q Technologies, Atlanta, GA) at an initial time point (T1) and one month later (T2). Principal component analysis was used to analyze the dynamics of lip movement, and dynamic time warping was used to evaluate the reproducibility between T1 and T2 for the individual facial gestures. Statistical analyses were used to compare the reproducibility of the different facial gestures.
  
  
  RESULTS
  All four verbal gestures were found to be significantly more reproducible than the nonverbal gestures. The word "puppy" was most reproducible, and the normal smile expression least reproducible. A hierarchy of reproducibility is proposed as "puppy," "baby," "rope," "bob," standardized smile, normal smile.
  
  
  CONCLUSIONS
  Verbal facial gestures, in particular the words "puppy" and "baby," are more appropriate for use in the assessment of lip movement when compared with smile expressions because of their high level of reproducibility over a one-month period.
authors.affiliation: Applied Clinical Research and Public Health, School of Dentistry, Cardiff University, Heath Park, Cardiff, UK. popath@cardiff.ac.uk
authors.forename: Hashmat
authors.initials: H
authors.lastname: Popat
authors.forename: Emma
authors.initials: E
authors.lastname: Henley
authors.forename: Stephen
authors.initials: S
authors.lastname: Richmond
authors.forename: Lanthao
authors.initials: L
authors.lastname: Benedikt
authors.forename: David
authors.initials: D
authors.lastname: Marshall
authors.forename: Paul L
authors.initials: PL
authors.lastname: Rosin
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005149:Facial Expression; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008046:Lip / Q000502:physiology; D008297:Male; D009068:Movement; D010780:Photogrammetry; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D012904:Smiling / Q000502:physiology; D055815:Young Adult