Coupling and lateralization in bimanual coordination at 7, 8, and 9 years of age

Abstract

We studied the role of the preferred hand in bimanual coordination using an apparatus like the X‐Y plotter first described by Preilowski (1975). Subjects were children of 7 to 9 years, an age period when Iaterality, hemispheric interaction, and bimanual coordination have been demonstrated to change. The task required the children to draw a pattern by rotating two cranks either at the same velocity or with a 2:1 velocity ratio, with parallel or mirror movements. Although subjects moved their two hands at the same velocity with relative ease, the right‐hand output of right‐handers significantly exceeded their left‐hand output. At age 7, the error was less systematically deviated toward the right‐hand‐controlled axis using parallel as opposed to mirror movements. This difference did not persist at 8 and 9 years of age. When subjects were required to move one hand twice as fast as the other, performance did not vary as a function of which hand moved faster. However, the lines drawn were more wavy in the left‐hand‐faster than in the right‐hand‐faster condition as long as visual feedback was provided. These results suggest that a unilateral control of the two hands as a coordinative structure occurs earlier when interhemispheric interaction is not a critical factor.