The Mona Lisa Gaze Effect

Abstract The Mona Lisa effect is the phenomenon in which certain portraits appear to direct their gaze at observers almost regardless of where observers are located with respect to the picture. This phenomenon has been well known for almost 2,000 years, yet it has not been studied much. The effect does not essentially depend on the motion of the observer. Rather, the effect is due to the fact that perception of gaze direction of a “looker” does not depend only on the position of the irises within the sclera but also on the orientation of the looker’s head with respect to the observer.