"Optimal" lateralization on the Tapping Test

The present study was designed to test the general "imbalance" hypothesis in regard to the Tapping Test, a motor measure of finger-oscillation speed from the Halstead-Reitan neuropsychological battery. The study was prompted by a recent spate of reports linking cerebral lateralization to a variety of conditions. It was hypothesized that it would be possible to determine an "optimal," midrange of lateralization, to be identified by faster tapping speeds. As hypothesized, those offenders with "moderate" laterality achieved faster speeds than those with "extreme" laterality ("extreme" defined as either less or more laterality than for the moderates). The same range appeared optimal over several demographic groups. A second goal of the present study was to pursue hints from a previous study that had suggested a lateralization measure might prove to be free of some unwanted variations by demographics. As hypothesized, the lateralization measure appeared free of variations according to age, sex, and handedness. Applications and future directions were suggested.