Analysis of the JND of Stiffness in Three Modes of Comparison

Understanding and explaining perception of touch is a non-trivial task. Even seemingly trivial differences in exploration may potentially have a significant impact on perception and levels of discrimination. In this study, we explore different aspects of contact related to stiffness perception and their effects on the just noticeable difference (JND) of stiffness are surveyed. An experiment has been performed on non-deformable, compliant objects in a virtual environment with three different types of contact: Discontinuous pressure, continuous pressure and continuous lateral motion. The result shows a significantly better discrimination performance in the case of continuous pressure (a special case of nonlinearity), which can be explained by the concept of haptic memory. Moreover, it is found that the perception is worse for the changes that occur along the lateral axis than the normal axis.