title: Age- and fatigue-related markers of human faces: an eye-tracking study.
abstract: OBJECTIVE
  To investigate the facial cues that are used when making judgments about how old or tired a face appears.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Forty-seven subjects: 15 male and 32 female participants, ranging from age 18 to 30 years.
  
  
  METHODS
  Forty-eight full-face digital images of "normal-appearing" patients were collected and uploaded to an eye-tracking system. We used an Applied Science Laboratories (Bedford, MA) Eye Tracker device associated with gaze-tracking software to record and calculate the gaze and fixation of the participants' left eye as they viewed images on a computer screen. After seeing each picture, participants were asked to assess the age of the face in the picture by making a selection on a rating scale divided into 5-year intervals; for fatigue judgments we used a rating scale from 1 (not tired) to 7 (most tired).
  
  
  METHODS
  The main outcome measure was gaze fixation, as assessed by tracking the eye movements of participants as they viewed full-face digital pictures.
  
  
  RESULTS
  For fatigue judgments, participants spent the most time looking at the eye region (31.81%), then the forehead and the nose regions (14.99% and 14.12%, respectively); in the eye region, participants looked most at the brows (13.1%) and lower lids (9.4%). Participants spent more time looking at the cheeks on faces they rated as least tired than they did on those they rated as most tired (t = 2.079, P<0.05). For age judgments, the eye region (27.22%) and then the forehead (15.71%) and the nose (14.30%) had the highest frequencies of interest; in the eye region, the brows and lower lids also had the highest frequencies of interest (11.40% and 8.90%, respectively). Participants looked more at the brows (t = -2.63, P<0.05) and glabella (t = -3.28, P<0.01) in those faces they rated as looking the oldest.
  
  
  CONCLUSIONS
  This study supports the hypothesis that age and fatigue judgments are related to preferential attention toward the eye region. Consequently, these results suggest that aesthetic or functional surgery to the eye region may be one of the most effective interventions in enhancing the appearance of an individual.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Harvard Department of Ophthalmology Boston, Massachusetts, USA.
authors.forename: Huy Tu
authors.initials: HT
authors.lastname: Nguyen
authors.forename: Derek M
authors.initials: DM
authors.lastname: Isaacowitz
authors.forename: Peter A D
authors.initials: PA
authors.lastname: Rubin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001288:Attention / Q000502:physiology; D003463:Cues; D005133:Eye Movements / Q000502:physiology*; D005145:Face / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult