Accession Number : ADA311411

Title :   Physiological Workload Reactions to Increasing Levels of Task Difficulty.

Corporate Author : DIRECTOR OF AIR FORCE RESEARCH AND DEVELOPMENT THE HAGUE (NETHERLANDS)

Personal Author(s) : Veltman, J. A. ; Gaillard, A. W.

PDF Url : ADA311411

Report Date : 21 JUN 1996

Pagination or Media Count : 32

Abstract : The sensitivity of physiological measures to mental workload has been investigated in a flight simulator. Twelve pilots had to fly through a tunnel with different Levels of difficulty. Additionally, they had to perform a memory task with four levels of difficulty. The easiest memory task was combined with the easiest tunnel task and the most difficult memory task with the most difficult tunnel task. Between each tunnel session, subjects had to fly a pursuit task in which a target jet had to be followed at a large distance. Rest periods before and after the experiment were used as a baseline for the physiological measures. Mental workload was measured with heart period, continuous blood pressure, respiration and eye blinks. Heart rate variability, blood pressure variability and the gain between systolic blood pressure and heart period (modulus) was derived from the measures. All measures showed differences between rest and flight, and between the pursuit task and the tunnel task. Only heart period was sensitive to the different levels of the tunnel. Heart rate variability is affected by respiration, and therefore, can only be interpreted together with the respiratory data. The modulus was hardly influenced by respiration and therefore, appears to be a better measure than heart rate variability. From the respiratory parameters, the duration of a respiratory cycle was the most sensitive to changes in workload. The time in between two successive eye blinks (blink interval) increased and the blink duration decreased as more visual information had to be processed. Increasing the difficulty of the memory task leaded to a decrement in blink interval, probably caused by subvocal activity during the rehearsal of the letters. Blink duration was not influenced by the memory load.

Descriptors :   *PERFORMANCE(HUMAN), *STRESS(PHYSIOLOGY), *HUMAN FACTORS ENGINEERING, *FLIGHT SIMULATORS, *WORKLOAD, *ROLES(BEHAVIOR), PARAMETERS, MEMORY(PSYCHOLOGY), PILOTS, TARGETS, SENSITIVITY, TUNNELS, CYCLES, VARIATIONS, MEMORY DEVICES, LONG RANGE(DISTANCE), RESPIRATORY SYSTEM, PHYSIOLOGY, VISION, RESPIRATION, PURSUIT COURSES, HEART RATE, MENTAL ABILITY, BLOOD PRESSURE.

Subject Categories : Aircraft
      Psychology
      Stress Physiology
      Human Factors Engineering & Man Machine System

Distribution Statement : APPROVED FOR PUBLIC RELEASE