Evaluating female pilot cadets′ mental workload by National Aeronautics and Space Administration-task load index and heart rate variability index

Abstract

Objective To compare the National Aeronautics and Space Administration-task load index (NASA-TLX) scores and the heart rate variability (HRV) of the female pilot cadets under different task conditions and to preliminarily investigate the characteristics of flight mental workload in females. Methods Two factors repeated measurement design was applied in this study. Twenty female pilot cadets of a flight college were chosen as subjects. Their ECG data was collected under the baseline status that they were in theoretical education and the states of preflight, taking off, approaching and landing in simulated and real flying tasks by KF1 physiological parameter recorder. The NASA-TLX scores were used to evaluate the subjective mental workload of the female cadets under baseline status and in all flying stages. The collected data are analyzed by repeated measurement ANOVA and the trends of changes in different flight stages were analyzed by Spearman′s non-parameter correlation test. Results Eighteen subjects′ NASA-TLX scores and 10 subjects′ HR and HRV data were valid. ①In analysis of the main effects of task type factors, 18 female pilot cadets′ NASA-TLX scores showed significant variance between different tasks (F= 8.294, P<0.01). The grand average scores both in simulated flight task (49.47±22.69) and in real flight task (49.68±16.85) were significantly higher than that of baseline status [(30.85±13.97); t=3.506, 3.547, P<0.05]. The heart rates of 10 female pilot cadets showed statistical significance between different tasks (F=14.615, P<0.01). The average heart rate in simulated flight task [(84.70±6.89)beats/min] and in real flight task [(87.73±8.79)beats/min] was also significantly higher than that of baseline status [(73.70±6.15)beats/min; t=4.029, 5.137, P<0.05]. ②At the stage of landing, NASA-TLX scores of 18 female flight cadets in real flight task (61.70±13.15) and in simulated task (60.54±21.05) were significantly higher than that of baseline status [(30.85±13.97); t=3.506, 3.547, P<0.05]. The HRV indexes of 10 female cadets, including normalized unit low frequency (LFnu), normalized unit high frequency (HFnu), ratio of low and high frequency bands (LF/HF), varied significantly in different types of task at the landing stage (F=9.015~12.275, P<0.01). The LFnu in simulated flight [(90.88±4.44)%] and real flight tasks [(77.22±12.04)%] was higher than that of baseline status [(63.75±16.87)%; ] (t=4.957, 2.462, P<0.05), and the HFnu of the two flight tasks [(9.11±4.52)%, (22.78±12.04)%] was lower than that of baseline status [(36.25±16.87)%; t=4.955, 2.460, P<0.05]. The LF/HF in this flight stage showed significant difference between simulated task (13.51±9.51) and baseline status [(2.40±1.66); t=4.088, P<0.05]. ③Both in the simulated and real flight tasks, the NASA-TLX scores of 18 female flight cadets showed rising trend with the flight stage progress (ρ=0.328, 0.537, P<0.01). The rising trends were also found on the LFnu and LF/HF of 10 female flight cadets (ρ=0.450~0.631, P<0.01) while the descending trends with flight stage progress were found on HFnu in both tasks (ρ=-0.631, -0.450, P<0.01). Conclusions The mental workload of female pilot cadets significantly increases in flight tasks as comparing to the baseline status and is significantly higher in landing stage than before flight. The simulated flight task can provide female pilot cadets basically the same mental workload as the real flight task. It is meaningful to pilot′s training and related researches. Key words: Gender identity; Workload; Cognitive; Psychophysiology; Work capacity evaluation; Electrocardiography; Mental workload