ABSTRACT
This chapter reports detailed analyses of writing data designed to provide a clearer idea of the generality and limits of effector independence in writing. Confirming previous observations of overall shape similarity across effectors, these analyses also reveal systematic changes in details of shape, kinematics, stroke decomposition, and fluency occurring with changes in effector. These results serve as the basis for reconsidering the implications of empirical effector independence in writing for the hypothesis that motor programs can be generalized to operate across effectors. Although strong assertions are premature, the results reported are consistent with the conclusion that writing by the dominant and the nondominant hands is carried out using different strategies that share only the very highest and most abstract spatial representations of what the shape of the writing should be. By contrast, writing with the dominant hand and the dominant arm appears to be controlled by mechanisms that share a common representation much lower in the hierarchy of increasing motor specificity particularly for highly overlearned productions such as one's name.
