A test person is sitting in a swivel chair. A second person has just stopped the rotation of the chair. The disoriented test person points at a sign held up by a third person.
The subject is placed in the chair, blindfolded, then spun about the vertical axis while keeping his head upright or tilted forward or to the side. The subject is then asked to perform tasks such as determine his direction of rotation while blindfolded, or rapidly change the orientation of his head, or attempt to point at a stationary object without blindfold after the chair is stopped. The chair is used to demonstrate spatial disorientation effects, proving that the vestibular system is not to be trusted in flight. Pilots are taught that they should instead rely on their flight instruments.
The device is also used in motion sickness therapy.