The Sensibility to Passive Movement of the Human Elbow Joint

Abstract

The literature on the perception of passive movement is reviewed. A description is given, of an apparatus whereby passive movements may be produced at the human elbow joint with the minimal amount of interference with sensation from extraneous factors. Tested with this apparatus, four human subjects experienced in varying degree false sensations of movement when the arm was at rest. They differed from each other in the direction which they tended to ascribe to the sensations, three of them being strongly influenced by the direction of the preceding movement. Both the perception of movement and identification of its direction were more efficient in extension than in flexion and at larger than at smaller displacements. The duration of movement was an important factor. Tentative estimates of the threshold are: 0·8° for 80 per cent, correct detection of movement and 1·8° for 80 per cent, correct identification of direction at all speeds in the range, 0.10·0.25°/sec.