Can left-handed writing posture predict cerebral language laterality?

B. T. Volpe, J. J. Sidtis and M. S. Gazzaniga

In terms of cerebral lateralization of function, left-handed persons represent a more heterogeneous group than right-handed persons. Some evidence suggests that left-handed subgroups can be identified on the basis of the following two types of writing posture: (1) inverted posture that indicates ipsilateral hemisphere language capability and (2) straight writing posture that indicates contralateral hemisphere language capability. A direct test of this hypothesis with an intracarotid amobarbital sodium injection failed to support these predictions. For clinical decisions in which the hemisphere subserving language is necessary, one should rely on direct assessment with the use of the amobarbital injection technique.