Figure 1.

Photo illustrating the experiment condition and the marker set-up (A), and an example of 3D movement registration (displacement of the corresponding markers) during (bimanual) light-switch task performance (pressing three light-switch buttons in a sequential, side-to-center order) (B). Starting positions of the hands are denoted by the small white circles at the lower end of the table in 1A and the white arrows denote the four directions studied (bottom–top, top–bottom, side–center, center–side).