Influence of Combined Vibration and Electrical Stimulation on Latency of Kinesthetic Illusion

The application of vibration stimulation to muscles, via the skin surface, can generate the sensation of movement, when actually there is no motion. This phenomenon is called kinesthetic illusion. Recently, in the fields of rehabilitation and virtual-reality technology, research has been conducted to utilize kinesthetic illusions to feel body movements, when there are none. To apply kinesthetic illusions in the above fields, it is necessary to develop techniques to improve the occurrence rates of the kinesthetic illusions and shorten the latency, which is the time lag from the onset of stimulation to the occurrence of the illusion. In a previous study, the authors reported that the occurrence rate of kinesthetic illusion could be improved by simultaneously applying vibration and electrical stimulations to the antagonistic muscles. In this study, the influence of this technique on the latency of the generated kinesthetic illusion is investigated by applying a combination of vibration and electrical stimulations. Three different electrical-stimulation voltages are used in the combined stimulation to induce the kinesthetic illusion, and the latency is studied for each voltage condition and the vibration-only condition. The effects of the voltage change on latency are evaluated from a regression analysis performed using the generalized linear mixed model. The results suggest that the change in the electrical stimulation voltage can shorten the latency of kinesthetic illusion.