Age- and Fatigue-related Markers of Human Faces: An Eye-Tracking Study

Purpose To investigate the facial cues that are used when making judgments about how old or tired a face appears. Design Experimental study. Participants 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). Main Outcome Measures 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