Figure 2.

Force field conditions and movements across the experimental design. The wrist configuration (flexed, neutral, and extended) is shown for the three columns at the bottom of the figure. A, The control group always performed movements in six directions with the neutral wrist configuration. B, The Cartesian group performed reaching six reaching movements with the same Cartesian direction and forces for all three wrist orientations. C, The object group. The six reaching directions were rotated for each wrist orientation such that the forces experienced were identical to the Cartesian condition (but rotated by 30°). D, For the anti-object group, the force field and the reaching directions rotated in the opposite direction to the wrist. However, the forces experienced still matched those of the other groups. Importantly, the force fields and reaching directions on the middle wrist configuration were identical across all four groups.