An officer at Air Force Space Command noticed that operators that were fatigued did not seem to perform as well as those operators that were well rested. He was interested if this observation was statistically significant and if added automation could help mitigate any negative effects of fatigue on monitoring and controlling satellites. He designed a study to look into this question. He recruited volunteers willing to participate in a sleep study. Participants would initially be restricted in sleep for a few nights, then would come in and perform tasks in a simulator that were representative of operational tasks. Participants would then be required to sleep 8 hours a night for a few nights, then would come in and perform the tasks in the simulator again. A sub-set of the simulator tasks were at a low level of automation and the remaining simulator tasks were at a high level of automation. a)[4 pts] What is/are the study independent variable(s)