Figure 2

Experimental setup of the numeric keypad. The index (1), middle (2), and ring (3) fingers of the right or left hand were placed on the numeric keyboard’s lower line, covered with a virtual partition. The digits 1, 2, and 3 corresponded to ‘1’, ‘2’, and ‘3’ keys for the right hand and to ‘3’, ‘2’, and ‘1’ keys for the left hand. For the 3rd and 4th conditions, the second line of the numeric keyboard was also involved and was indicated with red numbers on the screen. In this case, the digits 1, 2, and 3 corresponded to ‘4’, ‘5’, and ‘6’ keys for the right hand and to ‘6’, ‘5’, ‘4’ keys for the left hand. Images within the figure were drawn by János Négyesi and were scanned using Microsoft Office Lens application (Microsoft, Redmond, Washington, USA).