Jenkins and Dallenbach Did a Famous Study on the Phenomenon

Multiple Choice

Jenkins and Dallenbach did a famous study on the phenomenon of retroactive interference in the 1920s, in which they found that getting a good sleep before an exam might not be a bad idea. Which of the following was true about their study?

A) they tested two large groups: one slept between study and recall, and the other stayed awake
B) they found a main effect for retention interval but not for whether or not the participants slept
C) the design was a 2x4 repeated measures factorial design
D) the subject variables was whether or not the participants were able to sleep; the manipulated variable was retention interval