Contribution of the mandible position to the facial profile perception of a female facial profile: An eye-tracking study

Abstract

Studies concerning the visual attention of laypersons viewing the soft tissue facial profile of men and women with malocclusion are lacking. This study aimed to determine the visual attention to the facial profile of patients with different levels of mandibular protrusion and facial background attractiveness using an eye-tracking device. The scanning paths of 54 Chinese laypersons (50% female, 50% male, aged 18-23years) were recorded by an eye-tracking device when they observed composite female facial profile images (n=24), which were combinations of different degrees of mandibular protrusion (normal, slight, moderate, and severe) and different levels of facial background attractiveness (attractive, average, and unattractive). Dependent variables (fixation duration and first fixation time) were analyzed using repeated-measures factorial analysis of variance. For normal mandibular profiles, the fixation duration of the eyes was significantly higher than that of other facial features (P<0.001). The lower face and nose received the least attention. As the degree of protrusion increased from slight to moderate, more attention was drawn to the lower face accompanied by less attention to eyes in the unattractive group (P<0.05). When protrusion degree increased from moderate to severe, attention shifted from nose to lower face significantly in the attractive group (P<0.05). Attention shift from eyes to lower face was also found in the average group when protrusion degree rose to moderate protrusion from normal profile (P<0.05). A significant interaction between facial attractiveness and mandibular protrusion was found in the lower face duration (P=0.020). The threshold point (the point of mandibular protrusion degree that evoked attention to the lower face) of the attractive facial background was higher than that of the unattractive background. Once evoked, the effect of mandibular protrusion of the attractive group tended to be stronger than that of the unattractive group, though without statistical difference. Eyes are the most salient area. The increasing degree of mandibular protrusion tends to draw attention to the lower face from other facial features. Background attractiveness can modify this behavior.