The independence of horizontal and vertical dimensions in handwriting with and without vision

The purpose of this study was to investigate the relationship between horizontal and vertical components of handwriting production when subjects were instructed to vary the size of these components separately or together. The effect of vision on these instructed size transformations also was examined. Eight female adults participated in the experiment. The basic task was to write the words 'poppy' and 'wood' cursively five times, the first time in their normal size and then with four size transformations. These transformations--one-fourth, one-half, double, and four-times their normal size--were made under three different sets of instructions (width only, height only, both) and in two visual conditions (normal, blindfolded), for a total of six sets of five repetitions. The individual slopes (changes in actual values across the transformation values) for width and height under instructions to change both parameters were almost identical to the width and height slopes under instructions to change only the single parameter, supporting the notion of the independence of the horizontal and vertical components. Further, an analysis of these individual slopes indicated that the size transformations were significantly greater (p less than 0.05) (and closer to the instructed values) with vision than without vision.