Part 4: Eye Tracking and the Hatcher Illusion
So our brains are hardwired to see faces, but what does that have to do with smiles? Well it turns out that the smile is one of the most important features of the face and this can be confirmed with eye tracking studies. In these studies, a computer can register what parts of image the subject is focusing on. These studies confirm that when we look at the human face we spend most of the time looking between the eyes and the mouth. Most of our social cues come from these two areas, and our ability to read social cues may rely on this natural fixation. Studies on patients with Autism seem to indicate that they have an an altered gaze pattern when looking at faces. There are even studies that show that we when look at a smiling face, our eyes are drawn first to the smile itself first even before we look to the eyes!
Here is an example of how our gaze naturally focuses on the eyes and the mouth:
The Thatcher Illusion
Arising from our natural tendency to focus on the eyes and the mouth, comes a fun visual illusion called the “Thatcher illusion”. Look at the next two faces and you should find the one on the right far more disturbing than the one on the left:
The interesting fact is that these two images are exactly the same, only rotated 180 degrees. (You can turn your computer screen upside-down to verify that last statement). When the head is upside-down but we see the eyes and mouth are oriented correctly, it looks ‘ok’. Our brains don’t mind that too much. However, when we see the eyes and mouth upside-down on an upright face, it really looks bad! This illusion illustrates that when we look at a face, we really focus on the individual parts, the eyes and the mouth. This is why it is so important that these parts of our face represent us well!