The impact of visual cues on haptic compliance discrimination using a pseudo-haptic robotic system

A psychophysical magnitude estimation experiment was set up to determine the extent of the contribution of visual feedback during haptic compliance discrimination. Subjects remotely palpated physical compliant samples using a novel pseudo-haptic feedback system which allowed for independent manipulation of visual and haptic feedback. Subjects were asked to rate the compliance of a test sample based on that of a reference sample. While visual feedback was modified by switching the physical test samples shown to participants during indentation, haptic compliance of the test samples was always identical to that of the reference sample. Any variations in haptic sensation was a result of pseudo-haptic illusions. Ratings were collated and fitted to Steven's power law as well as Weber's law. A 0.18 power exponent suggests that the system was successful in generating viscoelastic properties through variations in visual information only. A 19.6% visual change from the reference compliance was necessary in order to perceive a change in haptic compliance using the pseudo-haptic system. These findings could prove beneficial in research and educationalfacilities where advanced force feedback devices are limited or inaccessible, where the concept of pseudo-haptics could be used to simulate various mechanical properties of virtual tissue for training purposes without the needfor complicated or costly force feedback.