Effects of Hypoxia on Voluntary Response Time to Peripheral Stimuli during Central Target Monitoring

Response times (RT's) of 10 Ss to the randomly occurring flashes of a centrally located stimulus light were obtained concomitantly with separate RT's to the randomly-ordered flashes of 48 other stimulus lights distributed peripherally throughout the visual field. Responses were obtained during separate 3 1/2 hour exposures to each of four hypoxic conditions (sea level, 13,000, 15,000, 17,000 ft). Analysis of variance of the results indicated systematic increases in RT and variability (SD) due to hypoxia, stimulus peripheralization, and their interaction which resembled the results of a previous study in which no central stimulus was used; however, the present RT's were smaller. The data indicate that, although the central task was more demanding, it acted to maintain alertness and thus reduce the hypoxic decrements in RT shown previously.