Question

A psychologist puts forth the hypothesis that REM sleep has the function of consolidating the memories from the previous day. The psychologist cites as evidence that when a person or animal is awakened during REM sleep, their memory for the events of the prior day (tested on awakening after the full night's sleep) is poorer than the memory of people who are not awakened. In order to interpret this result as evidence for a relation between REM sleep and memory formation, one would need the additional control of:

Answer 1

To establish a relationship between REM sleep and memory formation, a study must include a control group awakened outside of REM sleep, controlling for the act of awakening itself and confounding factors like emotional state and stress.

Step-by-step explanation:

In order to interpret the result as evidence for a relation between REM sleep and memory formation, one would need to include an additional control group of individuals who are intentionally awakened throughout the night, but not during REM sleep.

This control group would account for the effects of being awakened, as opposed to the effects of being specifically awakened during REM sleep. Furthermore, since REM sleep is also involved in emotional processing and regulation, it would be beneficial to measure not only memory consolidation but also emotional state and stress levels. This could help determine whether the disturbed memory for events of the prior day is due to the interruption of REM sleep specifically or due to the general stress and disruption caused by being awakened.