ABSTRACT
An increased incidence of left-handedness has been found among maths teachers and tertiary maths students and among a group of extremely mathematically-talented students. Relationships between ability and handedness occurred mostly in the 14-year-old data, suggesting that handedness effects appear around adolescence. Theories such as M. Annett and N. Geschwind's seek to relate the causes of left-handedness to the effects. As the organisation of cerebral function and the effects of factors such as sex and maturational change which interact with handedness become better understood, further insights into these aspects of individual differences will become possible. An intriguing hypothesis to explain this inconsistency was proposed by Annett and A. Turner. Using Annett's genetic model of handedness, they suggested that left-handers comprise several different populations. In one, left-handedness is associated with the 'absence of a genetic determinant', which also means that normal language development does not occur in the left cerebral hemisphere, whereas in the other, neuropsychological development is normal.
