Looking at the image pasted here I can't help but see the face on the right as the happier face. I see in my normal interactions the right half of the person's face as what is telling me what is going on. The right half of face happens to be in my left visual field and my right eye has to cross my midline to connect with their right eye. When I look at the linked image on the left I see a sad face on it's right side (my left visual field). If I attempt to reverse the process and put my attention in my left eye and cross the visual field to see the persona in their left face (my right visual field) I feel there is a postural adjustment that I make to relate to that person.
My tendency in myself that I have noticed over time is that I express my emotions and have better muscular control with my right half of face. (for example eyebrow movement). It is also my usual way to read another's face. The term for seeing the right half of another person's face (left visual field) is pseudoneglect and is common for the majority of people. (approx 75%).
PS Somehow I really screwed up my left and right on the first go
ps cool cat