Spatial bias: The surprising case of left-handers as evidence for an embodied interpretation

People show a systematic preference for the trajectory implied by the writing direction of their language. For example Italian or English participants prefer rightward directed stimuli. Studies on this spatial bias have provided contradicting evidence for the role of handedness on the direction and strength of such bias. Given that movements inward the body are more difficult than outward movements, the rightward hand movements while writing are more difficult to perform for left- than right-handers, whereas the rightward eyes movements during reading are equally difficult. In line with an embodiment perspective, we advance that the spatial bias is related to the effort implied in the directed movements involved in writing and reading activities and we therefore expect a different spatial bias between right- and left-handers in a drawing task, but a similar bias in a perception task. Two studies compare left- and right-handers in tasks involving figure drawing (exploring a motor spatial bias) and image perception (exploring a visual spatial bias). In line with the hypotheses, lefthanders participants showed a stronger motor spatial bias, whereas handedness did not affect the visual spatial bias. Together the results suggest that the strength of the effort that is necessary to perform rightward directed movements affects the intensity of the consequent spatial bias, confirming the embodied character of the bias and shedding light on the effect of handednes