[Maintenance of a steady level of vigilance during the electronystagmographic investigation (author's transl)].

During electronystagmography (ENG) a magnetic tape is used and with it simple arithmetical problems including the solutions are presented in time intervals of 15 seconds, the solutions being correct or incorrect in a random succession. The test person holds a simple electric bell in this hand having been instructed to press the bell-button once or twice, depending whether the announced solution is correct or not. During the recording of the ENG these signals are made visible as rectangular impulses on a separate trace, thus allowing control over the degree of cooperation of the test person. To prove the value of the described procedure 20 normal persons were investigated after sleep deprivation of one night with and without presentation of arithmetical problems, both investigations changing alternately. The evaluation of the parameters of ENG clearly demonstrates a significant difference in both experimental procedure, particularly in respect of frequency and angular velocity at the slow nystagmus phase. The described method has not only proved valuable for increasing vigilance but also not for maintaining a steady level of vigilance during the electronystagmographic investigation.