Asymmetry of left versus right unilateral cleft impairments: an experimental study of face perception.

Abstract

Previous psychosocial studies of adults born with cleft lip and palate have provided circumstantial evidence that surgically repaired right-sided unilateral clefts may be more disfiguring than left-sided clefts. The present study asked if such asymmetries are physiognomic asymmetries or arise "in the eye of the beholder," representing perceptual processes in face recognition. Color slides of 160 children (6 years of age) and young teenagers (16 years of age) were rated by subjects for perceived disfigurement. Sixty of the subjects had unilateral complete cleft lip and palate (30 had a right-sided cleft and 30 had a left-sided cleft), 60 had unilateral cleft lip/alveolus (30 right-sided and 30 left-sided clefts), 32 children had bilateral cleft lip and palate, and 8 children had cleft palate only. Faces were shown in normal and in mirror-reversed versions; the order in which faces were shown was randomized, as were other stimulus factors such as cleft type, age, and gender. The study was conducted as a classroom-type experiment at the Vision Laboratory, Department of Psychology, Oslo, Norway. Thirty-seven students of psychology at the University of Oslo, who were ignorant of the purpose of the study, acted as subjects. Subjects rated perceived disfigurement using a visual analog scale. Modest but highly consistent hemifacial asymmetries in judged disfigurement were found, with left-sided unilateral clefts rated as less disfiguring than right-sided unilateral clefts. Unilateral clefts were judged as being less disfiguring than the bilateral clefts, and cleft lip/alveolus was judged as being less disfiguring than cleft lip and palate. The patterns of facial judgments were almost identical in the normal and reversed-slides conditions. Asymmetries between left- and right-sided clefts reside in physiognomic factors rather than in hemispheric asymmetries controlling the perceptual process of face judgment.