Stroke direction asymmetry in figure drawing: influence of handedness and reading/writing habits.

Recent studies suggest that asymmetries noted in certain nonlinguistic tasks used in laterality research (e.g., facial affect judgment, line bisection) may in part be influenced by prior reading/writing habits. The present study examined the relative influence of reading/writing direction and handedness on the direction of stroke movement in free-hand figure drawing. One hundred twenty right and left handed brain-intact adult readers of scripts with opposing directionality (Hindi vs Urdu) and illiterate controls were observed while drawing a tree, a hand, a house, an arrow, a pencil, and a fish. Right-handers (including right-handed illiterates) and left-to-right readers drew most figures in a left-to-right direction, whereas left handers (including left handed illiterates) and right-to-left readers more often drew the figures from right to left. These results extend previous findings and contribute to a growing body of evidence demonstrating reading scan biases in nonlinguistic perception and production tasks. It would appear that reading/writing habits cannot be ignored as a potential artifact in studies of hemisphere functional asymmetry employing nonlinguistic stimuli.