Hemispheric asymmetry and interhemispheric transfer in pointing depend on the spatial components of the movement

The purpose of the present study was to compare the asymmetry and transfer in 3 pointing movements with increasing spatial requirements. The triggerin g signal was one of four visual targets appearing on the right or left of a central fixation point (FP). The first task consisted in simply removing t he arm from the starting platform; the second was a pointing movement towar ds the FP, and the third was a classical pointing task towards one of the f our lateral targets. 20 right-handers (Rhrs) and 20 left-handers (Lhrs) par ticipated in this experiment. In the classical pointing task (task 3), the reaction times were shorter in the Rhrs using their left hand. No such hand -related difference was observed in the Lhrs. No hand asymmetry was observe d in the other tasks. In addition, the responses were faster in the uncross ed than in the crossed conditions, in task 3 only. It was concluded that in pointing tasks, both the hemispheric asymmetry and the interhemispheric tr ansfer depend on the spatial requirements of the movement.