The lateralized effects of concurrent cognitive activity on a unimanual skill.

Laterality studies have long been plagued by: (1) poor psychological methodology; (2) lack of specification of treatment parameters' and (3) exclusive use of left-hemisphere dependent measures. It was suspected that a recent study by Kinsbourne and Cook (1971) suffered from these faults. The present experimental findings confirm these original suspicions. Both spatial and verbal cognitive tasks were employed and comparisons made with performance during two control conditions. One was a mixed spatial-verbal activity, the other control required S to merely look at a blank card. While left-hand performance was enhanced under the verbal concurrent activities, when compared with performance under control (spatial-verbal) conditions, no other significant enhancement of performance occurred with any other concurrent activity condition. With the "No Activity Specified" control some support for the Kinsbourne study was found. However, the major finding, or implication, of this study was in demonstrating that the methodological problems outlined above cannot be ignored if worthwhile laterality studies are to be performed.