Several basic characteristics of mental capacity were measured on 59 patients by means of computer-based-methods before and after oxygen multistep therapy (O2-MT) and compared with the results obtained from 14 volunteers serving as controls. Before and without O2-MT, an appreciable, age-dependent decline of the short-term memory capacity (general fluid intelligence) was found. O2-MT, completed by brain jogging, effected a significant increase in the presence duration by 0.4-0.7 secs, in the information flow by 1.4-1.9 bit/sec, resulting in an increase in the short-term memory capacity by 19-23% (in two experimental groups). The short-term memory itself was, however, not improved as compared to the controls. Moreover, the times needed for the accomplishment of perception, interference and reaction tests became significantly shorter by 12-18%. By using the screening test for cerebral insufficiency (CI), which is based on these parameters, the suspicion of CI could be excluded in 18 of 59 patients.