Intermanual coordination in relation to handedness, familial sinistrality and lateral preferences.

Intermanual coordination assessed by alternating finger tapping and finger-tapping asymmetry were investigated in 105 healthy right- and 105 left-handers and related to handedness, familial sinistrality and lateral preferences (in hand-clasping, arm-folding and eyedness). Compared to right-handers, left-handers with less pronounced left-hand preferences (Subgroup B) showed higher values in intermanual coordination and lower values in finger-tapping asymmetry. Moreover, familial sinistrality and eyedness interacted with handedness effects. While in right-handers intermanual coordination was significantly higher in subjects with dominant left eye, in left-handers of the Subgroup B it was somewhat higher in those with dominant right eye. Higher values in intermanual coordination and reduced asymmetry in finger tapping may be associated with a greater bihemispheric control and better performance in fast bimanual movements.