LONGITUDINAL-STUDIES OF BEHAVIOR AND PERFORMANCE DURING A WINTER AT THE SOUTH-POLE

Background: Evidence of a specific pattern of performance decrement in isolated and confined (ICE) environments has not been consistently de monstrated in previous research. Hypothesis: Decrements in performance in ICE environments: a) occur in a linear, dose-response manner; b) o ccur in stages; or c) do not occur at all. Methods: There were 83 memb ers 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. Results: Over the enti re 8-mo period, there was a decline in depression (p = 0.007) and vigo r (p < 0.0001), and an increase in fatigue (p = 0.059) and tension-anx iety (p = 0.075). Of these four measures, only vigor exhibits a linear pattern. Mean scores for tension anxiety and fatigue were lower durin g the first half of the winter than the second half (p = 0.074 and 0.0 77, respectively). In comparisons between each quarter and the remaini ng three quarters, averaged mean tension-anxiety scores and fatigue sc ores were lower during the second quarter (p = 0.009 and 0.03, respect ively), and higher during the fourth quarter (p = 0.025 and 0.035, res pectively) than during the previous three quarters combined. Conclusio ns: The duration of optimal performance in isolated and extreme enviro nments and the explanation for changes in performance during long dura tion assignments in such environments both depend on what behavioral m easure is used to assess performance.