Comparing force magnitudes by means of vibro-tactile, auditory, and visual feedback

The objective of this research was to study the suitability of multi-modal sensory substitution for force-feedback. This substitution is appealing because sound force feedback requires large, heavy, and expensive equipment. In a series of experiments we investigated the substitution of force feedback in judging objects\´ properties related to the kinesthetic perception. "Forces" of varying strength were presented by vibro-tactile, visual, or auditory feedback, or combinations thereof. We tested the suitability of substitutes in two manipulation experiments: in the first, the participant had to judge the "weight" of cubes relative to each other; in the second, the participant had to judge the amount of force necessary to move a brick due to frictional resistance. The trials were performed using a partially immersive desktop virtual reality system and a CyberTouch data glove that provides vibro-tactile feedback. Results show that just one substitute is sufficient to successfully complete the task. However, the task performance, in terms of correct discrimination and time, improved when a combination of substituting stimuli was presented.