An investigation of proprioception illusion using a stimulator with feedback control

It is possible to create illusions of limb movements using vibrations over the skin. If a muscle is vibrated it can feel as if the limb is moving while it remains still. These illusions have been studied for decades but it is not yet entirely clear how to create them effectively and repeatedly. In this study, three parameters were varied; the frequency of the vibration, the stimulation site and the arm position. A closed loop control of the vibration frequency was used to ensure a fixed frequency over the stimulation time and across the participants. The experiment included twenty-five able-bodied participants (mean age 32±7 years, 9 females). A hanging arm position was introduced with the aim to increase the success rate of illusions compared to other studies. Twenty-four participants felt an illusion across all scenarios. The results highlight that tactile feedback affects the illusion.