Longitudinal studies of behavior and performance during a winter at the South Pole

Evidence of a specific pattern of performance decrement in isolated and confined (ICE) environments has not been consistently demonstrated in previous research.

Decrements in performance in ICE environments: a) occur in a linear, dose-response manner; b) occur in stages; or c) do not occur at all.

There were 83 members of the United States Antarctic Program who spent an austral winter at the Amundsen-Scott South Pole Station (90 degrees S) between 1991 and 1994 and completed the Profile of Moods States (POMS) once a month for an 8-mo period from March through October.

Over the entire 8-mo period, there was a decline in depression (p = 0.007) and vigor (p < 0.0001), and an increase in fatigue (p = 0.059) and tension-anxiety (p = 0.075). Of these four measures, only vigor exhibits a linear pattern. Mean scores for tension-anxiety and fatigue were lower during the first half of the winter than the second half (p = 0.074 and 0.077, respectively). In comparisons between each quarter and the remaining three quarters, averaged mean tension-anxiety scores and fatigue scores were lower during the second quarter (p = 0.009 and 0.03, respectively), and higher during the fourth quarter (p = 0.025 and 0.035, respectively) than during the previous three quarters combined.

The duration of optimal performance in isolated and extreme environments and the explanation for changes in performance during long duration assignments in such environments both depend on what behavioral measure is used to assess performance.