PhD, University of Cincinnati, 2007, Arts and Sciences : Psychology

Gravity-induced loss of consciousness (GLOC) is a major psychophysiological threat to pilots of high-performance aircraft that has resulted in substantial loss of life and equipment (Albery &Van Patten, 1991). It is brought about by a sudden reduction in cerebral blood flow and subsequent decrease in cerebral tissue O2 as a result of increased +Gz force (McKinley, Tripp, Bolia, & Roark, 2005). During such episodes, pilots are totally incapacitated for 24 sec. They are unconscious for half of that time (the absolute incapacitation period) and confused for the remainder (the relative incapacitation period; Whinnery, Burton, Boll, & Eddy, 1987). In addition, evidence is available to indicate that cognitive and psychomotor functions are compromised several sec prior to the onset of unconsciousness and for 55.50 sec after confusion subsides (Tripp et al., 2006). Using centrifuge simulators to induce GLOC and math and tracking tasks to emulate flight performance, three experiments were conducted to determine if reductions in the rate of G-suit deflation (Experiment 1), the application of supplementary sensory stimulation (Experiment 2), and the employment of negative Gz offset profiles (Experiment 3) could be of effective value in reducing the duration of the GLOC epoch. All three experiments produced statistically significant reductions in the duration of the epoch, but these reductions were too small to be of practical utility in an operational setting. Experiment 3 also featured the use of near-infrared cerebral oximetry to track the course of cerebral tissue O2 levels in a GLOC-inducing experimental session. The results indicated that O2 levels dropped precipitously from baseline after the onset of Gz acceleration with performance deterioration beginning and GLOC appearing when the O2 levels fell to 95 percent and 80 percent of baseline, respectively. Cerebral oxygen levels rose quickly after the termination of acceleration and returned to baseline well before partici (open full item for complete abstract)

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Cognitive