Captain David Minard, with the medical corps of the U.S. Navy, discusses tests conducted for 44 days in Korea to study the physiological and psychological stressors on troops under actual combat and fatigue. Using a chart, he explains the test for reactivity of the autonomic nervous system. Both attack and defense troops were measured before and after combat for hormone excretion, protein destruction, body salt retention, white blood cell count, and number of days to recover. Capt. Minard recommends using electronic transducers and transmitters to record such data in the future. Jean Taylor, an operations analyst with Johns Hopkins University, explains homeostasis (adjustments to protect the status quo) and the results of serious strains on it. Combatants were given paper and pencil tests to measure their higher mental functions and given a visual flicker fusion frequency test and an auditory flutter fusion frequency test to measure sensory cortical sensitivity. Ms. Taylor concludes that the physiological tests were more definitive than the psychological tests, which were inconclusive. Psychological stress was best observed through films shown of men before and after a combat that resulted in a 61% casualty rate. The men's physiological reactions followed Hans Selye's chart of response to stress: alarm reaction, resistance stage, exhaustion phase.