Left-handedness and spatial reasoning abilities: The deficit hypothesis revisited

Left-handers with an inverted handwriting posture have been found by Levy and Reid to have relatively bilateral representation of tachistoscopically tested verbal and spatial functions. On the assumption that such bilateral representation is inefficient, it was hypothesized that left-inverted subjects (N = 20) would score lower than left- and right-handers with normal handwriting postures (Ns = 64, 66 respectively) on spatial reasoning. Results were consistent with the hypothesis. Possible alternative explanations and directions for future research are outlined.