Researchers found that the left side of an individual's face is more likely to be perceived as more pleasing than their right side.
Researchers, Blackburn and Schirillo examined if there was a difference in the perception between the left side of the face in real-life photos of people. In the study, volunteers were asked to rate the pleasantness of 56 female and male faces, with each having a mirror image of the other.
Pupil dilation was used as a preference as it is unbiased and unconscious. When pupils dilate, an individual feels something he sees more attractive to him. They dilate when they see something unpleasant.
They found most participants rated the left side of the faces (both male and female) to be more pleasing than the right side, although the right-sided face was the original orientation of the faces. According to the authors, "the poser's left cheek exhibit greater intensity of emotion, which observers find more pleasing."
"...These results are consistent with the view that the underpinning of human facial beauty is complex and that bilateral symmetry does not constitute a principle factor in beauty assessment,” according to Dahlia W.Zaidel and Marjan Hessamian of the Department of Psychology, University of California, LA.
Their research is published online in the journal, Experimental Brain Research.