Evolution of degree and direction of hand preference in children: Methodological and theoretical issues

This paper presents some methodological and theoretical issues based on a longitudinal study, performed in schools, on hand preference of 256 children, initially aged 3-6 years. Three phenomena are observed: (1) the well-known asymmetry of the hand preference distribution, which probably depends on biological factors; (2) a weak ''towards the right'' tendency with increasing age, which could be explained by environmental factors; and (3) a strong increase in the degree of hand preference with age which could be a consequence of the subject's own activity. Handedness is considered here as a possibly interesting model to delineate the respective role of biological, environmental, psychological, and pathological factors involved in a simple human behaviour.