Answer:
Dependent variable
Explanation:
Memory is the dependent variable in this context, since the researcher is trying to test the effect of sleep deprivation (independent variable) on memory (dependent variable). Thus, the variation of the experimental treatment would be applied to the sleep deprivation - perhaps by using a control group (people who did not experience sleep deprivation), or creating different sleep deprivation length to test if there are differences in the quality of memory encoding, storage, or retrieval.