There are Chimeras, where faces are split and then mirrored - my own Chimera even scared me...
The basis for facial assymetry has been the subject of research by Paul Ekman (inspiration for Lie to Me TV program) and this old post
The early work of Paul Ekman in the evaluation of facial expressions is mentioned in the chapter, Facial Expression, in the textbook, Nonverbal Behavior in Interpersonal Behavior (5th ed), (Ekman, (1973) in Richmond & McCrosky, 2004). However, Paul Ekman and his peers have conducted a great deal of research in the study of facial expression since the early years when his Facial Affect Scoring Technique (FAST) became the standard used by researchers in the field of affect displays (Rozin & Cohen, 2003). FAST is based on six recognizable facial expressions (sadness, happiness, anger, surprise, disgust and fear).
The recent research has expanded in two directions. The list of easily recognized facial expressions has been lengthened and the research of cerebral hemispheric specialization has spun off investigations of asymmetrical facial expression. Perhaps, the most intriguing concept revealed by these two branches of research is that human facial expressions involve not just two areas of the face, eyes and mouth, but rather four areas; the left and right hemifaces, which each can be divided into the eye and mouth areas.
Of course, communication involves, at least, two people, so that analysis of nonverbal communication, in the form of facial expressions, requires observations and explanations for changes in eight facial areas.
Ekman, himself, was in the forefront of the critics of the FAST system of analysis. He said that faces could express eighteen different types of information of which emotions are only one type (Ekman, (1978) in Rozin & Cohen, 2003). Subsequent investigations have shown that a number of other expressions are easily recognized. Puzzlement, confusion, worry and concentration are four that are mentioned by Paul Rozin and Adam B. Cohen (Rozin & Cohen, 2003). Ekman lists disbelief and skepticism as examples of non-emotional facial expressions (Ekman, (1978,1979) in Rozin & Cohen, 2003).
Needless to say, the expansion the list of research verified recognizable facial could be a never-ending process. There are hundreds of words used to describe human nonverbal behavior and many of them have corresponding facial expressions. Words such as concern, affectionate, antagonistic, domineering, submissive and passive will undoubtedly be linked to particular configurations of facial muscles, at some point of time.
The research into the difference of facial expressions displayed on the right and the left hemifaces has uncovered an interesting relationship. The right hemiface displays expressions associated with approach behaviors, while the left hemiface displays expressions associated with withdrawal behaviors (Davidson, Saron, Senulis, Ekman, & Friesen, 2006). It almost seems as if the mechanism responsible for the flight or fight response is also responsible to some degree for hemifacial orientations.
It has been known for some time that the right hemisphere of the brain is the hemisphere where most emotional processing occurs, while the left hemisphere processes most verbal and language information (Root, Kinsbourne & Wong, 2006). Verbal abilities might develop from the nonverbal approach, as, perhaps, the neurological structure that causes this hemifacial distinction is also responsible for verbal behavior as language can be seen as ‘remote’ approach behavior. Research dealing with the facial expression of infants supports this hypothesis. Adult facial expressions are more apparent on the left hemiface, because in the mature brain the right cerebral hemisphere processes emotional data.
