INFORMATION COMPLEXITY - MENTAL WORKLOAD AND PERFORMANCE IN COMBAT AIRCRAFT

The purpose of the present study was to analyse the effects of informa tion complexity on Pilot Mental Workload (PMWL) and Pilot Performance (PP), and to analyse the structure of PMWL. Eighteen pilots performed 72 simulated low level-high speed emissions. The complexity of the Hea d Down Display (HDD) information varied as a function of the tactical situation. Flight data were recorded continuously. The pilots' eye mov ements were video taped and psychophysiological activation data, Heart Rate (HR), were obtained. The pilots rated PMWL according to the psyc hological content of three scales (Bedford Rating Scale, Subjective Wo rkload Assessment Technique, NASA-Task Load indeX) and answered a ques tionnaire tapping aspects of performance, information load, motivation and mood. It was found that even a moderate complexity of information interfered with the flight task. Altitude and variation in altitude w ere increased and corrections of altitude errors were delayed, when co mplexity increased. Changes in information load reached its maximum in fluence on flight performance (r = 0.60, p < 0.001) after a time delay of 20 to 40 seconds. Performance of the flight task correlated positi vely (r = 0.59,p < 0.001) with the performance of the information hand ling task (Tactical Situation Awareness, TSA). Durations and frequenci es of eye fixations Head Up (HU) versus Head Down (HD) changed as a fu nction of information load. A structural equation model implied that P MWL was affected by mission complexity and that PMWL affected objectiv e and subjective aspects of flight performance and information handlin g. Heart rate (sortie means) correlated positively with PMWL (r = 0.34 , p < 0.05) and perceived complexity of mission (r = 0.37, p < 0.01). Heart rate (running means) covaried with variations in information com plexity for those pilots who performed well. From spectral analyses of cardiac interval times it was found that the amplitude of the 0.10 Hz component tended to decrease during high as compared to low levels of information load.