Directionality Trends as a Function of Handedness and of Reading and Writing Habits

The handedness and the acquired reading and writing habits of the subjects were specifically varied, to examine their effects on directionality trends in the subjects' drawing of figures with horizontal extensions. The right-handers were relatively unaffected by reading and writing habits that opposed innate tensor tendencies, the left-handers significantly affected. It is suggested that these directionality trends in the horizontal dimension may reflect some aspect of lateralization of cerebral function and that in mature adults the mixed-dominance lefthanders are more influenced by environmental factors than are right-handers. Directionality is the tendency of a movement to pursue a characteristic course under given conditions. The phenomena of directionality are extremely complex in the human organism. The present paper reviews directionality trends in the drawing of horizontally extended figures and specifically investigates the influence of reading and writing habits and of handedness on directionality in adults. It is generally accepted that tensor movements outward from the body are superior to flexor inward movements. The former have been described by several authorities as being smoother, more rapid, more accurate, and less fatiguing (Bartlett, 1957; Brown, Knauft, and Rosenbaum, 1948; Downey, 1932). This phenomenon could be due to neuromuscular or central characteristics. In either case, right-handed subjects would be expected to draw horizontally extended figures from left to right and left