Rapid Dual-Task Decrements After a Brief Period of Manual Tracking in Simulated Weightlessness by Water Submersion.

Objective: Investigating dual-task (DT) performance during simulated weightlessness by water submersion, using a manual tracking and a choice reaction task. In contrast to previous work, we focus on performance changes over time.

Background: Previous research showed motor tracking and choice reaction impairments under DT and single-task (ST) conditions in shallow water submersion. Recent research analyzed performance as average across task time, neglecting potential time-related changes or fluctuations of task-performance.

Method: An unstable tracking and a choice reaction task was performed for one minute under ST and DT conditions in 5 m water submersion and on dry land in 43 participants. Tracking and choice reaction time performance for both tasks were analyzed in blocks of 10 seconds.

Results: Tracking performance deteriorated underwater compared to dry land conditions during the second half while performing one minute in DT conditions. Choice reaction time increased underwater as well, but independent of task time and type.

Conclusion: Tracking error increased over time when performing unstable tracking and choice reaction together. Potentially, physiological and psychological alterations under shallow submersion further strain the human system during DT operations, exceeding available recourse capacities such that DT performance deteriorated over time.

Application: Humans operating in simulated weightlessness underwater should be aware of substantial performance declines that can occur within a short amount of time during DT situations that include continuous tracking.