A Predictive Model of Cognitive Performance Under Acceleration Stress

Abstract

A Predictive Model of Cognitive Performance under Acceleration StressExtreme acceleration maneuvers encountered in modern agile fighter aircraft can wreak havoc on human physiology thereby significantly influencing cognitive task performance. Increased acceleration causes a shift in local arterial blood pressure and profusion causing declines in regional cerebral oxygen saturation. As oxygen content continues to decline, activity of high order cortical tissue reduces to ensure sufficient metabolic resources are available for critical life-sustaining autonomic functions.Consequently, cognitive abilities reliant on these affected areas suffer significant performance degradations.This goal of this effort was to develop and validate a model capable of predicting human cognitive performance under acceleration stress. An Air Force program entitled, "Human Information Processing in Dynamic Environments (HIPDE)" evaluated cognitive performance across twelve tasks under various levels of acceleration stress.Data sets from this program were leveraged for model development and validation.Development began with creation of a proportional control cardiovascular model that produced predictions of several hemodynamic parameters including eye-level blood pressure. The relationship between eye-level blood pressure and regional cerebral oxygen saturation (rSO 2 ) was defined and validated with objective data from two different HIPDE experiments. An algorithm was derived to relate changes in rSO 2 within specific brain structures to performance on cognitive tasks that require engagement of iv different brain areas. Data from two acceleration profiles (3 and 7 G z ) in the Motion Inference experiment were used in algorithm development while the data from the remaining two profiles (5 and 7 G z SACM) verified model predictions. Data from the "precision timing" experiment were then used to validate the model predicting cognitive performance on the precision timing task as a function of G z profile. Agreement between the measured and predicted values were defined as a correlation coefficient close to 1, yet complex factor in overall system design. Moreover, many find it convenient to develop the mechanical system separately from the HO and then rectify the interface between the two as the system is being prepared for production. One of the central issues contributing to this ill-advised strategy is the inability of the designer to easily change the inherent characteristics of the human entity. Should a material used in the "skin" of an aircraft react inappropriately to extreme temperature changes, the material can be replaced with an alternative material with properties that allow it to remain inert and invariable with respect to temperature. However, the human element cannot be replaced with a stronger, faster or lighter component. The HO performance characteristics can only be augmented to a limited extent with modern technology, training, and procedures.However, even with the assistance of such technology aids, the HO often reac...

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