Performance evaluation tests for environmental research (PETER): code substitution test.

The effects of repeated testing on code substitution performance were studied in three experiments to determine reliability and stability of task performance under laboratory and at-sea conditions. In Exp. 1, a single 2-min. testing trial per day was administered to a group of 19 subjects for 15 consecutive weekdays. In the second experiment a 4-min. per-day test was administered to 12 of the 19 original subjects for an additional 15 consecutive weekdays. In Exp. 3, six US Coast Guardsmen were tested hourly for four consecutive days, two days at dockside and two days at sea. In Exps. 1 and 2, means, variances, and cross-session correlations became stable after Day 8. Stabilized reliabilities were .75 for Exp. 1 and .80 for Exp. 2. The results of Exp. 3 were comparable to those obtained in the first two experiments with the exception that decrements in performance corresponding to high frequencies of motion sickness symptoms occurred during the at-sea trials. The Code Substitution Test is recommended for inclusion in the PETER battery.

Development of performance evaluation tests for environmental research (PETER): navigation plotting.

A navigation plotting task, modeled after actual shipboard navigation and plotting practices, was evaluated for inclusion in the Performance Evaluation Tests for Environmental Research (PETER) task battery. The differential stability of the 9-min self-paced task was examined independently in the laboratory and during a field study conducted at sea aboard three seagoing vessels. Repeated testing in both laboratory and field conditions showed that the percent correct metric was not reliable. After 10-15 practice trials, the total completion and total correct scores were found to meet minimum statistical stability and reliability criteria. Inclusion of the Navigation Plotting task in the PETER test battery is recommended given the task's direct operational validity, its demonstrated sensitivity to vessel motion and motion sickness, and the degree of statistical stability and reliability found with the total completion and total correct metrics.

Susceptibility to seasickness: influence of hull design and steaming direction.

Three sea going vessels steamed side by side through slight seas off the coast of Oahu, Hi. A 4-h octagon was transmitted twice each day for three consecutive days while motion sickness symptomatology was recorded from 18 enlisted men who alternated among the vessels. Dramatic differences in illness severity were obtained whether comparisons were made using objective evidence of vomiting episodes or subjective reporting of symptoms on questionnaires. Reliability of this scoring method was excellent (r = .95). In addition to face and construct validity, evidence is presented of the predictive validity of the scoring method in a separate octagonal steaming experiment using a 95 ft Coast Guard patrol boat in an equivalent experimental paradigm. This study showed significant covariance between the magnitude of motion sickness symptomatology and the encounter direction of the vessel to the primary swell (p less than 0.01). Additionally, significant correlations were found between sickness severity and test subject concentration, fatigue, urine production, and urine specific gravity. The majority of these relationships would not have been disclosed had only the dichotomous criterion of vomit/nonvomit been employed in assessing motionsickness severity. Implications of these data as design criteria for marine vehicles are discussed.