Enhancement of range of creation of foot sole tactile illusion by vibration stimulation of the foot instep*

Abstract

We previously developed a method for augmenting tactile sensation on the toepad. By presenting vibration to the toenail while the toepad contacts a surface, an illusory tactile sensation can be induced on the toepad. Importantly, this method does not require users to attach a rigid actuator to the sole. However, the illusory sensation is restricted to a limited area. In the current study, we tested a proposed method for extending the range of the illusory tactile sensation in the foot sole by applying vibration stimulation to the foot instep. In a preliminary experiment, we identified that stimulating the first and fifth metatarsal tips induced a tactile illusory sensation on the foot sole. In the first experiment, the probability of occurrence of tactile illusion was determined, and the effectiveness of our presentation method was confirmed. In the second experiment, we determined the load conditions under which the illusion occurs. The results suggested the feasibility of use during walking. Our findings indicated that the range of the illusory tactile sensation on the foot sole can be expanded by stimulating the first and fifth metatarsal tips in addition to the toenail.