The present paper demonstrates that study of human motion behaviour can be usefully assisted by Virtual Reality (VR) techniques, building upmotion tasks in which subjects interact with virtual instead of real objects. A tool is introduced by which an experimenter can easily build up VR-based reach to grasp experiments. Virtual objects are presented to the test subjects by means of a viewer centered projection onto a high resolution graphics monitor. Experiments for the visual perception of viewer centered visualized objects show that inaccuracies, resulting from the curved surface of the screen, and discrepancies between convergence and accomodation, can be neglected when the negative parallax is not too large. Using the developed tool, the results of a first experiment related to the study of human motion behaviour are presented, which show that VR-based experiments can indeed lead to concrete hypotheses about human movement organization: the results suggest that not only the transport and the grasp component are represented by two separate visnomotor channels in the human brain, but that also the grasp component itself is divided into two separate programs, one for the acceleration phase and the other for the deceleration phase of a reach to grasp movement.
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