Two-dimensional portraits generate a strong perception of eye contact. I remember the posters of rock stars in my friend’s room when I was a kid. When I walked around in the room, Alice Cooper’s gaze appeared to follow me. The phenomenon, known as the Mona Lisa effect, is well studied and documented. However, as we discovered in a recent study, the Mona Lisa effect is not the only phenomenon that explains the magic-like appeal of two-dimensional portraits of rock stars and enigmatically smiling ladies.
As a model poses for the photographer, they often look directly in the lens of the camera; eye contact (mutual gaze) creates captivating photographs. When an observer then looks at the resulting two-dimensional image, both eyes of the observer receive a direct gaze. This condition is in contrast with a natural setting where people look at either the left or the right eye of each other at a time. Thus, the two-dimensional photograph or painting provides a perception of eye contact that is stronger than possible in a three-dimensional real-life setting.
The implications of the results are manifold; two-dimensional portraits are widely used in emotion and gaze research. However, our results indicate that using two-dimensional portraits reduces the ecological validity of the results, i.e., the results may not apply in real-life situations. The results were published in the open-access journal Journal of Vision.