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.