Cerebral concussion may produce subjective disturbances for a considerable period without being associated with objective clinical signs. Since dizziness is one of the most frequent complaints, it has been assumed that the vestibular apparatus is frequently affected by concussion. Vertigo as a symptom complaint is subjective. Tests for this condition (Romberg test; deviation test; finger to nose test) depend on the patient's cooperation, and their significance is often easily appreciated by the patient. These tests are difficult to apply in cases of malingering. Because of its objective nature, one of the best tests available is the nystagmus reaction to caloric stimulation. Since the nystagmus reaction may be normal in patients with considerable disturbance, the presence of a pathologic nystagmus response would indicate objective impairment, but a normal nystagmus reaction would not exclude it. The variability of the nystagmus effect may be partly due to the judgment of the observer. Hence,