ABILITY TO DETECT ANGULAR DISPLACEMENTS OF THE FINGERS MADE AT AN IMPERCEPTIBLY SLOW SPEED

The ability to detect very slow rotations, which were associated with no sense of movement, was tested at the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of the middle finger of human subjects. This ability was termed ‘position sense’. All the joints were found to have a position sense. No difference in detections of different angular displacements was demonstrated between the joints. Contraction, after the completion of a displacement, of the muscles operating the joints did not alter the position sense. In addition, the DIP joint was also examined in a posture that functionally disengaged its flexor and extensor and no change in position sense was found.