Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Richard F. Ferraro


The present study examined the effects of time of day of testing on a simulated aviation task. The tasks required the participants to engage in multitasking while electroencephalogram (EEG) data was collected to objectively measure participants’ workload. Task demands were altered throughout the testing period to expose participants to both high and low workload conditions. Additionally, individual differences in circadian rhythm were explored by assessing participants’ circadian typology. No significant differences in performance were found resulting from time of day differences. However, performance and EEG differences were found based on phase of testing and workload manipulations. Subjective workload measures were influenced by time of day, with a moderating effect of circadian typology. Implications are discussed.