Enhancement of Perceived Force from the Hanger Reflex on Head and Ankle by Adding Vibration

The "Hanger Reflex" is a phenomenon in which a participant involuntarily rotates their head when a wire hanger is attached it, and has also been observed on the wrist and the ankle. Moreover, the force caused by the Hanger Reflex on the wrist is enhanced by adding a vibration stimulus. These phenomena might be potentially useful for the rehabilitation of movement disorders characterized by abnormal posture. In this paper, we generalize this “vibration effect” on the Hanger Reflex by applying vibration to the head and ankle. We developed devices to generate both skin deformation and vibration, and conducted a user study. We observed that all participants perceived the enhancement of the force, and slightly rotated the stimulated parts of the body.