Abstract Background The subjective haptic vertical (SHV) task requires subjects to adjust the roll orientation of an object. mostly in the roll plane. in such a way that it is parallel to perceived direction of gravity. Previously we found a tendency for clockwise rod rotations to deviate counter-clockwise and vice versa. https://www.roneverhart.com/Plastic-Jigger-with-Measuring-Lines-Box-of-12/