Repeated Assessment of Stress,Mood and Performance Changes Resulting from Exposure to Vessel Motions at Sea

A preliminary study was conducted with six experienced male Coast Guardsmen and a small monohull vessel (95' Coast Guard Patrol Boat) to evaluate the feasibility of a proposed experimental paradigm as well as the sensitivity of an array of performance, physiological and affective state measures to vessel motions and motion sickness. Performance measures (e.g. Navigation Plotting, Critical Tracking, Visual Search, Complex Auditory Monitoring, Grammatical Reasoning, etc.), physiological measures (e.g., motion sickness severity, stress hormone excretion, urine output and specific gravity), and affective state measures (e.g., mood dimensions) were sampled continuously for eight hours each day for three consecutive days. All variables were compared between control (dockside, engines running) and steaming conditions (four-hour octagonal steaming patterns were repeated twice each eight hour day). Results show all physiological measures examined to be sensitive to the Influence of vessel motions or motion sickness. Motion sickness severity was found to rise and fall depending upon the encounter direction of the vessel to the movement of the primary swell; steaming courses with head or bow seas produced significantly greater degrees of illness than did courses possessing stern or quartering seas. Vessel motions led to significant increases in crew fatigue and changes in concentration. Some performance tasks (e.g. Navigation Plotting and Visual Search) were degraded at sea despite the potential contribution of practice effects, habituation to stress and motivation to perform. The Implications of such factors are discussed In terms of past, current and future performance assessment paradigms utilizing repeated testing.