Vibration research is reviewed from the point of view of how this environmental stress affects different types of human performance capabilities. The oscillatory motions normally called vibration range from 1–30 Hz., and the motion may be either sinusoidal or random. In terms of subjective discomfort, the lowest tolerance level for vibration occurs at about 5 Hz., the frequency at which resonance of large body organs is most severe. Visual acuity is severely impaired by vibration frequencies in the range of 10–25 Hz. Manual tracking capability is most seriously affected by vibrations at 5 Hz. and below, as are other motor capacities. Tasks involving primarily central neural processes, such as reaction time, monitoring, and pattern recognition, are highly resistant to the effects of vibration.