AMBIDEXTERITY, the ability to use both the right and the left hand with equal ease (Lat. ambi both, dexter right handed). Educationalists and physiologists frequently advocate the cultivation of ambidexterity in children on the ground that the brain-centres controlling the motor functions thereby become more highly developed. Since, however, the left hemisphere of the brain controls both the function of speech and the motor func tions of the right side, over-development of left-handedness has been known to cause speech impediment and must be avoided.
See F. W. Mott, The Brain and the Voice in Speech and Song (191o) ; H. Macnaughton Jones, Ambidexterity and Mental Culture (1914)•