Publication Date


Document Type


Committee Members

S. Narayanan (Advisor)

Degree Name

Master of Science in Engineering (MSEgr)


A cognitive model illustrating decrement in human performance as a function of increased G-forces has been highly sought after by the Department of Defense (DoD) for various reasons. The F-16 and other air combat platforms are super-agile aircraft that are easily capable of imposing G-forces on a pilot that are beyond human physiological limitations. Knowledge of these physiological limits and more importantly the resultant restrictions in cognitive function could prove invaluable to those who design and pilot such aircraft. The model may be utilized in the construction of improved flight simulators that incorporate more realistically performing enemy targets and therefore enhance the training of the air warfighter. Command and control functions may also benefit from a thorough understanding of the boundaries of human cognition in these dynamic environments. NTI is a research firm based in Fairborn, Ohio that has formulated just such a model. NTI has devised this model while contracted by the USAF Air Force Research Laboratory (AFRL) under a Phase II Small Business Innovation Research (SBIR) grant. The three primary principles that are employed in the NTI models' construction are the T-matrix, a previously developed G-effective model and the G-Performance Assessment Simulation System (G-PASS) battery of tests. The T-Matrix concept has been developed emulating the Educational Testing Service (ETS) Q-Matrix with the exception that it is based on cognitive tests as an alternative to interview questions. The G-Effective Model is based on the fact that human performance is not decremented by increased G-Forces encountered by the air warfighter instantaneously. Rather, a decrease in performance is the result of a subsequent reduction in cerebral blood flow that is in turn affected by both the G-profile as well as the onset rate of imposed G-forces. The G-PASS battery of tests is intended to be performed in the Dynamic Environment Simulator (DES) human centrifuge at the Air Force Research Laboratories (AFRL) Human Effectiveness Protectorate-G (HEPG) located at Wright Patterson Air Force Base. These tests are utilized to probe critical cognitive functions that are essential to pilots of combat aircraft. Results of a descriptive comparison of the NTI model versus the composite data obtained from the DES experimental results are presented in this thesis. Results show that the decrement of cognitive function as a result of increased Gz forces obtained in the HEPG experiments is consistently lower than what is predicted by the NTI model. These results may be partially accounted for by the fact that the NTI model is based on relaxed G conditions, whereas the DES experimentation was performed utilizing G-suits, positive pressure breathing and straining maneuvers.

Page Count


Department or Program

Department of Biomedical, Industrial & Human Factors Engineering

Year Degree Awarded


Included in

Engineering Commons