The purpose of the present study is to assess the influence of auditory and haptic signals on the manipulation performance in a virtual reality-based hand rehabilitation system. A personal computer, a tracker, and a data glove were included in this system. Three-dimensional virtual environments were developed. Forty volunteers were recruited to participate in a pick-and-place procedure, with three levels of difficulty and four feedback modes. Task time and collision frequency were the parameters used to evaluate
their manipulation performance. It can be concluded that the haptics is a significant signal for improving a subject's performance at the high difficulty level.