Speed and Accuracy of Aimed Hand Movements in Left-Handed Human Subjects: Sex-Related Differences in Motor Control

Abstract

Speed and accuracy in hand speed in relation to sex-related differences were studied in left-handed normal subjects. Hand skill was assessed by a peg moving task. Hand speed increased linearly with successive trials (motor learning). Left-hand speed exhibited a higher learning capacity than right-hand speed. Right-hand speed and right-hand learning were equivalent in males and females. Left-hand speed was higher in females than males; left-hand learning was equivalent in males and females. Left minus right (L-R) hand speed decreased linearly with right-hand speed; left-hand speed did not influence L-R hand speed. Learning curves were constructed for each subject. Standard error of a learning curve was considered as accuracy of hand skill. In females, accuracy of hand movement decreased as hand speed increased. In males, only accuracy of right-hand speed decreased as right-hand speed increased; left-hand accuracy did not depend on left-hand speed. It was concluded that right brain controlling left hand in left-handers has a higher capacity than left brain for motor learning; L-R hand speed was largely determined by left brain; accuracy in hand skill depends on both brains in females, and on only left brain in males; the female brain is more bilaterally organized than male brain in fine motor control.

Key Words:

• Hand skill
• motor learning
• sex
• left-handedness
• cerebral lateralization