A tactile display device including a nodule having variable stiffness under a surface to provide a near-real feeling of palpation for a physician. The device utilizes granular jamming technology using pneumatic actuation to control a nodule that maintains its shape while allowing the modulation in stiffness. The nodule includes two hemispheres, a contact portion and an actuation portion, forming a sphere. The contact portion and the actuation portion include different thicknesses and/or materials, while the dimensions of the dimensions of the nodule are maintained. As such, a physician can utilize the device to identify the difference between a normal lump and an affected lump even if the shape of each lump appears to be the same. With the tactile display device, due to the different levels of stiffness, a physician can detect the severity of the lump.