Development of laterality: Asymmetrical human behaviors and perceptual biases

Many asymmetries characterize human functioning at the behavioral level, such as handedness (right-handedness, left-handedness, mixed-handedness) and the cerebral level. Atypical laterality is frequently mentioned in scientific literature as part of the clinical picture of several neurodevelopmental and psychiatric disorders. Thus, understanding the neurodevelopmental mechanisms underlying laterality could shed light on the etiology of cognitive and motor difficulties. The goal of this thesis is twofold. Firstly, the theoretical objective was to investigate the involvement of the prenatal environment in the development of handedness. The influence of the vestibular system, fetal presentation, and other perinatal factors related to pregnancy complications and birth stressors were tested. Our results show no influence of the fetal presentation on the subsequent development of handedness. Perinatal adversities such as prematurity, low birthweight, and poor neonatal health reflected by very low Apgar scores however, appear to be risk factors which increase the prevalence of atypical handedness and motor impairments. Secondly, the applied objective was to simultaneously detect the different perceptual biases implicated in graphomotor productions. A 3D-2D transcription graphic task was proposed for identifying global patterns of drawing asymmetries, underpinned by cerebral lateralization, biomechanical constraints, and sociocultural influences. Our results suggest that cerebral lateralization, modulated by handedness and sex, influence graphomotor asymmetries in both children and adults. However, this influence is weaker in adults, which could be due to sociocultural influences.