In one of the studies discussed in Section 4.1.1 on the influence of sleep on memory Gais, Lucas, & Born (2006)

had participants learn German vocabulary word lists in the evening at 8 p.m. and then tested them on their recall of the words. There were no significant differences between the two groups on the number of words remembered on this first test. Half of the participants, the “sleep condition,” were then sent home to sleep, and half of the participants, the “sleep deprivation condition,”

stayed at the lab and were prevented from sleeping until 6 a.m. when they were allowed to go home and sleep.

Recall of the vocabulary words was again tested for both groups 48 hours after their initial learning. Participants remembered more of the learned vocabulary when they had slept during the night following learning than when they had stayed awake. Given these specifics about the research study, answer the following questions:

1. What research method did Gais et al. use to test their hypothesis?

2. Identify the independent and dependent variables in this study.

3. What is the best way for Gais et al. to have determined whether a participant was a part of the “sleep condition”

versus the “sleep deprivation condition”?

4. Name one potential confound in this study.