Kinesthetic Perceptual Symmetry in Bi-Manual Interactions: An Exploratory Study

In this paper, we present a study to explore the symmetry of kinesthetic perception. Our goal is to add to the growing literature that investigates haptics technologies for therapeutic and rehabilitative applications. To this end, we study how selective activation/ deactivation of haptic (specifically force) feedback affects human perception during symmetric bi-manual (two-handed) spatial tasks. We conducted a simple experiment where healthy individuals are tasked with stretching a virtual spring using two symmetrically located haptics devices that provide an equal amount of resistive forces on each hand while pulling the spring. In this experiment, we implement four kinesthetic conditions, namely (1) feedback on both hands, (2) feedback only on dominant hand, (3) feedback only on non-dominant hand, and (4) no feedback as our control. Our first goal was to determine if there exists a range of spring stiffness in which the individual incorrectly perceives bi-manual forces when the feedback is deactivated on one hand. Subsequently, we also wanted to investigate what range of spring stiffness would lead to such perceptual illusions. Our studies show that not only does such a range exist, wide enough so as to be potentially utilized in future rehabilitative applications. Interestingly, we also observe that for few cases, symmetry can be independent of the kinesthetic perception.