When both contours were presented in the lower visual field (see below figure, the first three slashed bars of the left bar group), the direction of perceived contour displacement was consistent with that when both contours were presented in the right visual field, e.g. a perceived displacement in the direction of the more eccentric dots. However, this illusory motion-induced spatial displacement disappears (see below figure, the first three slashed bars of the right bar group, not significantly different from zero) when both contours were presented in the upper visual field. This result pattern is likely due to a greater sensitivity to centripetal motion in the lower visual field (but no such a bias in the upper visual field) for human participants.