Effect of altitude and medication on directional error.
(A) Average predicted margins of directional error at peak velocity during post-sleep recall (Post-sleep rec, circles), immediate recall (Immediate rec, squares) and 60° adaptation (60 deg adapt, triangles) in the groups using Placebo (Plac) and acetazolamide (AZA) at 760 m baseline and at 3100 m altitude. (B) Average marginal effects on directional error at peak velocity (with 95% confidence intervals) of groups at baseline (Difference at BL, without drug); (C) effects of altitude (Altitude effect); and (D) effects of acetazolamide at 3100 m (AZA effects).