Images featuring faces prominently — even non-human faces — can be effective for gaining a viewer's attention. We’re all human and nothing interests and attracts us more than other humans. We’re hard wired to see faces and instantly be attracted to that person’s gaze.
You’ll notice in the image below that the model facing the camera and making direct eye contact, gets more attention than the person facing right.
We also use other people’s gaze as a way of guiding our own. In the video below you can see how people start off by looking at the left baby and then follow his gaze to the baby on the right.
Faces are important in advertising and marketing because our eye gravitates toward a face. Eye gaze is an impactful way to lead your audience visually to what you want them to see.