A set of devices for measurement of human balance orientation and eye movements in weightlessness was developed for neurovestibular experiments on Spacelab. The experiments involve astronaut motion, limb position changes, and moving visual fields, measurements are made of eye movements, muscular activity and orientation perception.This joint US/Canadian research program represent a group of closely related experiments designed to investigate space motion sickness, any associated changes in otolith-mediated responses occurring during weightlessness, and the continuation of changes to postflight conditions. The otoliths are a component of the vestibular apparatus which is located in the middle ear. It is responsible for maintaining the body's balance. Gravitational pull on the otoliths causes them to constantly appraise the nervous system of the position of the head with respect to the direction of gravity. The major objective is to determine how the body, which receives partially redundant information from several sensory mechanisms, reorganizes to account for the loss of usable information from one channel (the vestibular system) because of an environmental variation (loss of gravity). A second experiment objective is to investigate the cause of space motion sickness.The inflight experiment consist of five sub-experiments, each identified as a functional objective (FO). A sixth sub-experiment, FO7, consists of the preflight and postflight testing. Each of these sub-experiments is described separately.