Design of Robot-Assisted Task Involving Visuomotor Conflict for Identification of Proprioceptive Acuity

A deficiency in proprioception caused by some nerve injuries could result in movement disorders. An effective assessment of proprioception for patients with nerve injuries is essential for their rehabilitation. When visual input is inconsistent with motor input, humans tend to depend heavily on proprioception to perform a task. Based on it, we designed a novel robot-assisted task to identify proprioceptive acuity. We developed a robotic device to provide RM of wrist and employed VR immersing technology to present VM for a user. The RM and VM were programmed randomly to be consistent or not (conflicting) for each trial. The user was required to decide whether what they were perceiving (real motion) and seeing (virtual motion) is consistent or not in a total of 36 trials. We recruited 40 healthy participants (20 males and 20 females) for the assessment validation. The outcome indicated that the novel robot-assisted identification is sensitive enough to distinguish the difference in proprioceptive acuity between males and females. The male participants have better proprioceptive acuity of the wrist than the females ( $p < 0.05$ ), especially in the P/S motion $p < 0.005$ ). In addition, the gender difference was found in the sensitivity of proprioceptive acuity ( $p < 0.05$ ) while no difference was found in the specificity ( $p > 0.05$ ), indicating that female participants had poorer performance on the identification than the males when the RM is consistent with VM. This study indicated that the novel robot-assisted task is effective to identify limb proprioceptive acuity.