In our research project we examined the influence of facial symmetry on attractiveness. According to evolutionary theory faces are supposed to be more attractive the more symmetrical they are. In order to test this hypothesis we produced symmetrically optimised versions over a range of different faces (of low, average and high attractiveness). Each of these symmetrically optimised faces was presented to test subjects together with the corresponding original face. The task was to select the face that was perceived as being more attractive.
There are several ways of producing symmetrical faces: The most common
method is creating so-called "chimeric faces". Using image processing software,
one half of the facial image is duplicated, mirrored along a vertical axis
and finally added to the remaining half of the original face. The resulting,
perfectly symmetrical face consists either of two left or two right halves
of the original face. But there is one problem: Because faces are not perfectly
symmetrical, it does make a difference whether you use the left or the
right half as a starting point. Another problem is that, by using this
method, birthmarks, pimples or irregular hair structures are doubled, too,
so that the overall resulting symmetrical face looks quite odd.
Left: Symmetrical face using the left half of the original face. Middle: Original face. Right: Symmetrical face using the right half of the original face.
A clearly advanced and better way to produce individual symmetrical faces is the morphing technique. Morphed images are made from two images of different faces by averaging face shape and then blending red, green and blue intencity (RGB colour) across comparable pixels. All symmetrical faces we used in our research project were generated by blending together the original face with a duplicate that has been mirrored along a vertical axis.
In contrary to the Chimaerengesicht, the resulting face does not show a distinct dividing line along the centre of the face, and the question which half to take becomes obsolete.
Example: If a face has a broad left and a narrow right lower jaw, the mirror image method produces a face with either a broad or a narrow lower jaw on both sides. Avoiding these unpleasant effects, the morphing method automatically calculates the average breadth of the left and right half of the lower jaw.
In addition, asymmetries like a high-standing or slant eye are levelled out by this method. For our project we used a modified morphing procedure that symmetrized only the face proportions. Skin and hair remained unaltered, which made the resulting face look more natural and life-like.
Left: Symmetrically optimised face calculated by using
the conventional morphing technique; bad skin is ameliorated, hair gets
blurred, every single feature is reflected, facial hairs and pimples included.
The results from our experiment regarding 'symmetry' show that facial
symmetry affects the perceived attractiveness. However, the effect is rather
small and by far not as influential as it has been reported in the media.
To sum up our findings: Very asymmetric faces are judged rather unattractive,
but very unattractive faces are not necessarily asymmetric. And vice versa
: very symmetrical faces need not necessarily be judged attractive and
very attractive faces often show deviations from perfect symmetry (see
Based on our results, symmetry only seems to be a rather weak indicator
for attractiveness. Often it is even difficult to distinguish between the
original and the perfectly symmetrical version, because irregularities
in shape are rather insignificant. Therefore, the strong influence of symmetry
that has been reported in the scientific literature over and over again
Last modified: 01-07-2002, webmaster