Geometric transformations of handwriting as a function of instruction and feedback

Abstract

The present study explores whether the vertical and horizontal components in a well-learned skill like handwriting can be independently modified. Three experiments are reported. In the first experiment subjects were able to change voluntarily the horizontal or the vertical orientation of their writing with only minimal effect on the other component. In the second experiment an attempt is made to induce subjects to change the slant of their writing spontaneously by providing real time distorted feedback of either the horizontal or vertical components of their writing or both. Although little spontaneous adjustment to the distortions was found, when subjects were instructed to note and to compensate for the distortion independent modifiability of the horizontal and vertical components was again observed. In the third experiment it was shown that it is difficult to modify the size of either the vertical or horizontal component without a proportional modification of the other. The finding that the directions of horizontal and vertical components can be modified independently but their sizes cannot, is interpreted in terms of different control modes for direction and size parameters in handwriting.