Directional Bias in Representational Drawings of Graspable Objects by Right and Left Handers: The Contribution of Affordances vs. Biomechanical Principles

Abstract

This study investigated the orientation of representational drawings of everyday, graspable objects by right- and left-handed adults. Two competing hypotheses were examined. One was an affordance-based hypothesis which predicted that the graspable position of objects would be positioned in the side of space in which they are normally interacted upon. This effect was expected to be enhanced for objects involving self-directed movements (e.g., cup, toothbrush) than object-directed movements (e.g., hammer, tennis racket). The other was a biomechanical hypothesis, which predicted left placement of graspable portion of the objects be drawn by right handers and right placement by left handers, reflecting a greater ease of executions of outward directed movements. Sixty English-speaking right handers and 37 left handers each drew a total of 20 graspable objects. An overall left placement of graspable portions of objects was found, regardless of object movement type. With one exception (jug), the left bias was greater in right handers in 17 of the 20 objects. The results indicate that a biomechanical account provides a better explanation of drawing direction biases than an affordance account.