A developmental study of the influence of cognitive activity on an ongoing manual task

The present study investigated developmental changes in the lateralized effects of concurrent cognitive activity on the performance of a manual task. Children aged 9, 10, 11 and 12 years were required to press a key continuously for 15 sec whilst at the same time engaging in three conditions involving cognitive activity (spatial, verbal and mixed spatial-verbal probelem solving) and a control condition. The nature of the concurrent cognitive activity was found to produce differential effects on left- and righthand performance with spatial-cognitive activity being a more effective disruptor of an ongoing, left-handed manual task at the age of 9 years. Above that age verbal and spatial activity appear to have comparable disruptive effects.