We investigated how artificial tactile feedback in the form of a skin-stretch affects perceptions of stiffness and grip force adjustment. During interactions with objects, information from kinesthetic and tactile sensors is used to estimate the forces acting on the limbs. These enable perceptions of the mechanical properties of objects to form, and the creation of internal models to predict the consequences of interactions with these objects such as feedforward grip-force adjustments to prevent slippage. Artificial tactor displacement-induced skin stretch can produce a linear additive effect on stiffness perception, but it remains unclear how artificial stretch affects the control of grip force. Here, we used a robotic device and a custom-built skin-stretch to manipulate kinesthetic and tactile information. Using a stiffness discrimination task, we found that adding artificial tactile feedback to a kinesthetic force can create the illusion of touching a harder spring which affects both perception and action. The magnitude of the illusion is linearly related to the amplitude of the applied stretch. We also isolated the contribution of tactile stimulation to the predictive and reactive components of grip force adjustment, and found that unlike other cases of perceptual illusions, the predictive grip force is modulated consistently with the perceptual tactile-induced illusion. These results have major implications for the design of tactile interfaces across a variety of touch applications such as wearable haptic devices, teleoperations, robot-assisted surgery and prosthetics.
|Publisher||Cold Spring Harbor Laboratory Press|