Human tracking performance changes during combined +Gz and +/- Gy stress.

An experiment has been conducted on the centrifuge to examine roll-axis tracking performance in both static and stress environments. The stress environments were +5 Gz from 95 s and combined +5 Gz/+/- 1 or +/- 2 Gy for 95 s. Compared to the static condition, performance decrements of 19% were measured at +5 Gz, 45% at combined +5 Gz/+/- 1 Gy, and 70% at combined +5 Gz/+/-2 Gy. Heart rate increases were noted during the stress environments but no significant heart rate differences were noted between the +5 Gz and the combined +5 Gz/+/-2 Gy conditions. The conventional lap belt and shoulder harness restraint system, while not optimum, was adequate for these G environments.