Kurenkova, A.I.

Background. The uniqueness of human face perception mechanisms and their variability has become a subject for extensive investigation and wide discussion in the recent decades. While now the concept that human face is perceived as a whole is taken as a fact, the same cannot be said about the structure and methods to measure holistic processing. In the present study the factor of symmetry is investigated as one of the possible aspects of configural processing of facial perception.

Objective. The aim of the study was to apply the inversion method to the investigation of how distortion of facial configuration perception impacts the rating of its symmetry/asymmetry.

Sample. 54 participants (24 female and 30 male) aged 18 to 68 (mean age 26) took part in the study.

Method. An intra-individual experimental design was used. Participants rated asymmetry of normally oriented and inverted face-stimuli on a five-point scale. To set the symmetry level, left eye and/or mouth regions were rotated around their fiducial points, there were three rotation angles for each feature region. Zero asymmetry faces were created by blending halves of normal and mirror images of the sample face-stimulus. The mean asymmetry subjective ratings were submitted to repeated measures analysis of variance and paired samples t-test.

Results. The study revealed significant differences in the asymmetry ratings of upright and inverted faces: normal upright faces with rotated features were rated as more asymmetric compared to inverted. Thus, we may conclude that symmetry perception is affected by inversion. It was also revealed, that the effect of the eye region and the lips region rotation were not equivalent: the higher the level rotation of the eye area was the more significant the difference between the rates of upright and inverted faces was, while rotation of the lips area did not result in higher difference between the rates.

Conclusion. The observed face-inversion effect in the perception of symmetry in facial stimuli suggests that (a)symmetry is a component of holistic (configurative) processing of human face perception. At the same time, the contributions of individual features to the overall facial configuration may differ.