[Ontogenesis of lateralities. A review and attempted interpretation]

The present paper offers an updated review on lateralization development in normal children. Instead of just citing a voluminous litterature, we prefer to present an interpretation which perhaps is too synthetic but which tries to go beyond the frequent contradictions encountered within experimental studies as well as between the studies themselves. Results plead for a double movement in the human development, first towards a species-specific asymmetry, then towards a differentiated symmetry. We propose different advantages for the development of human competencies and for the underlying neuro-behavioural organization: asymmetry corresponds to phases in the intrahemispheric cerebral organization and symmetry to phases of interhemispheric synergy.