Performance during mild acute hypoxia.

: The controversy regarding the effects of mild hypoxia on learning performance needs to be resolved, since this may be affecting flight operations and safety. This study examined the ability to learn new tasks at low altitudes. Naive subjects (n = 144) performed spatial orientation (Manikin), serial choice reaction time (SCRT) and logical reasoning (Baddeley) tasks at ground level and at altitudes of 1,524 m (5,000 ft), 2,438 m (8,000 ft), 3,048 m (10,000 ft), and 3,658 m (12,000 ft), at rest or during exercise (VO2 = 600 ml O2.min-1) in a hypobaric chamber. Each task was performed over four serial repetitions (blocks) and presented at ground level or one of the four test altitudes in a first session, and in the reverse order in a second session. Performance for the Manikin and SCRT tasks improved significantly (p < 0.0001) over the 4 blocks. No significant difference was found between the corresponding 4 blocks of the first session in resting and exercising subjects tested at ground level before altitude compared to altitude before ground level. In general, RT for the 3 tasks were faster in resting than in exercising subjects. These results indicate that the ability to learn new tasks is not impaired by mild hypoxia at altitudes of up to 3,658 m. We detected a biphasic response to altitude in LRT and SCRT performance, but not for Manikin performance.