Experimental Study On Assessment Criteria For Judging Healthy Youths' Physiological Index And Cognitive Ability

It is one of the most important issues to monitor and prevent flight fatigue in the field of aerospace medicine. Fatigue, lack of sleep, and circadian disruption caused by long-haul, irregular, night and crossing time zone flight operations can degrade performance, alertness and safety. The aim of this study is to find the changing regulation of aircrew's physiological indexes such as HRV,pupil pore diameter,stereoscopic vision,blood vessel diameter of eye ground,video-nystanography,heterophoria and cognitive ability with a focus on pupil aperture and heart rate variability of the corresponding curves of the operators to conduct an objective, scientific, accurate, systematic evaluation, and further study adaptive physiological state pilot selection criteria. By means of dynamic monitoring of the aircrew's physiological status, their psycho physiological conditions can be found, which will ensure flight safety and prevent accident.It is general agreement that in-flight mental workload is a multidimensional construct, and there is no uniform standard to measure at present. Many factors can cause mental fatigue, and its performance is often induced by factors related to the commonly used model of mental fatigue, including sleep deprivation, lack of oxygen, drinking et al. The indexes of autonomic nervous system are relatively common indicators. Psycho physiological measurements are of particular importance in the flight environment since they offer a non-intrusive method to collect objective data about the mental workload of pilots and other crew members. We select some corresponding test items based on airplane pilots'mostly behavior after their fatigue, their professional request and their practical circs. These tests must be sensitive to flight fatigue short time cost and with good reliability, validity and distinction, small studying effect, brief maneuverability. Research on mental fatigue in our country is just underway, most of which was experimental or flight simulator study, but little real flight assessments reported.In order to evaluated in-flight mental fatigue of pilots of various kinds of flight course and flight phase, in the present study psycho physiological measures were obtained. We collect to record the changes of multi-physiological parameters in the condition of drinking alcohol by NVG,ETC,FC,CC etc equipment of physical detection. At the same time,we also have three psych tests involving spatial circumgyrate test (SCT),numeral plus photic point test(NPPPT) and speed estimates test (SET),which is as the accuracy and response time as the test indexes. There is an exact correspondence between psycho physiological indexes and mental workload.The names and indexes of physiological tests were as follows:(1) Heart Rate Variability (HRV): including two postures as erect position and prostration position. The indexes of time domain contains Mean NN and SDNN while indexes of frequency domain contains LF,HF,TF and LF/HF.(2) Pupil Pore Diameter (PPD): including pupil gray scale histogram and pupil area.(3) Video-Nystanography (VNG): including leftward and rightward of OPTOKINETIC TESTS,TRACKING TESTS,velocity and latency of SACCADE TESTS.(4) Clement Clarke (CC): including stereoscopic vision of binocular nasal side,temple side and intermedius side,vertical and horizontal heterophoria and binocular chromatometry.(5) Fundus Camera (FC): including diameter of artery and vein in eye ground.The names and main purposes were as follows:(1)The Spatial Circumgyrate Test (SCT): To examine the ability of space cognition, judgment and inference.(2)The Numeral Plus Photic Point Test (NPPPT): To examine the ability of short–term memory, calculation ability and attention distribution and choices.(3)The Speed Estimates Test (SET): To examine space cognition ability of distance and prejudgment of pilot.The main results were as follows:(1) Among physiological tests, the results from these tests involving HF,LF,TF,pupil area,diameter of superior temporal vein,vertical heterophoria and left eye chromatometry have shown that under the different condition, these indexes are significantly different. However, other results are not highly satisfactory.(2) The linear regression equation between pupil diameter as dependent variable Y and SDNN,LF/HF as independent variable was: Y=215.198-0.217X₁+0.177X₂, LF/HF as X₁, which the coefficient of correlation was -0.143 (p< 0.05), SDNN as X₂,which the coefficient of correlation was 0.816 (p< 0.01).(3) The linear regression equation between dependent variable Y and independent variable X was: Y=2.688+1.19X₁+0.00028X₂-27.83X₃+22.68X₄ vertical heterophoria as X₁ and the coefficient of correlation was 0.810 (p<0.01), LF of erect position as X2 and the coefficient of correlation was 0.341 (p<0.05), left eye chromatometry as X3 and the coefficient of correlation was -0.535(p<0.05), pupil diameter as X4 and the coefficient of correlation was 0.632(p<0.05).The research conclusion of psycho physiological indexes to assessment on mental fatigue:1. There are obviously expressed that these physical tests are sensitive to the special ability request of mental fatigue. These tests can evaluate pilots'mental status sensitively by the corresponding software analyses and technique disposal.2. The reaction time and right rate of 3 psychological tests are significantly different under the condition of mental fatigue,which indicates that alcohol can cause the changes of cognitive ability on mental fatigue.3. Some psycho physiological indexes are significantly correlative and can regress the corresponding equations, which indicates that these indexes can reflect mental fatigue,but different power, the pupil aperture, the heart rate changeability and vertical heterophoria can evaluate the physiological psychology to a certain extent.4 .Whether the laboratory research physiological indexes could evaluate the work achievements and mental ability workload of pilot remains to be further probed, but the autonomic nervous physiological indexes evaluate the mental fatigue is one of latest research directions, with the cognition ability union, the accuracy is able to be improved greatly and the measure of the mental fatigue which caused by actual flight mission can be objectively, rapidly and atraumatically.In brief, this research shows that mental fatigue should not use the sole index to carry on the evaluation, which should do with multi-level and multiple perspective indexes simultaneously. As a result of the condition limit, this research only involves autonomic nerve physiology signal examination and the cognition ability characteristic of mental fatigue. The practically and reliability of the research methods and indexes depend on further verification and consummation.