Figure 1.

Cognitive speed, accuracy, and efficiency across cognitive domains relative to the 30-day head-down tilt bed rest (HDBR) period (gray background) for the CO₂ group (3.73 mmHg CO₂, n = 11, 6 men) and the control group (ambient CO₂, n = 8, 6 men). Estimates reflect unadjusted means ± standard error z-transformed based on baseline (pre-HDBR) performance within each of the 10 Cognition tests and then averaged across tests. To reflect the analytical approach (adjusting for baseline performance), means were shifted within groups to reflect a pre-HDBR baseline performance of 0. The dashed line between the last HDBR administration and the first recovery phase administration in the control group indicates that this group spent 30 additional days in HDBR relative to the CO₂ group. HDBR, head-down tilt bed rest.