With the Manometer Task (MNT) cognitive performance can be examined under conditions of constantly elevated mental load. An adaptive algorithm continuously adjusts the task difficulty in accordance to the previous individual performance. The task concept is described and the psychometric properties are reported for the recommended MNT-configuration with data of N = 2084 candidates. The results showed that the mean reaction times are unrelated to the performance quality of the respective individual. Although, the individual performance quality showed moderate stability across the three levels of task complexity (.32 < r < .34), we did not observe substantial correlations to other tests of cognitive performance. Gender differences were insignificant. Also, age correlations are small (r < .10). Several examples of different practical applications showed how the MNT can be applied to monitor individual performance under the influence of different external stressors