When FDR took office and made his Inaugural speech the people's reactions seemed neutral. Although I wouldn't say they were happy there were some things they didn't agree with like the New Deal that FDR wanted to create this is because the people thought this New Deal was giving the government too much power and was involved in telling businesses how to operate.
Despite that New Deal situation the people of the country didn't seem to mind FDR they felt a little bit of hope especially since he was there for a lot of people during the Great Depression and WWII which has the saying 'the only we have to fear is fear itself.' Another thing people admired about him is facing all of those challenges between Germany and Japan which made him a defining figure in America. After he helped the people during the Great Depression people voted for him again giving him the win for re-election.
The time the mood of the country changed was after FDR's death in 1945 everyone was shocked over his sudden death but his Vice President, Truman had to take over his spot (as what the law suggests if something happens to the president i.e death or corruption in the result of jail time the Vice President has to take over). People were also concerned by Truman's action after he took over the office because it was still during WWII. Everyone mourned and had a lot of anxiety because of not knowing what's going to happen next.
Reason: That's because when their are two predators who eat the same animal their animal species will decrease because of new predators that will eat them!
The variable is the group that was given caffine, because thats what the doctors manipulated. They possibly altered the natural memory of the participants by giving them caffine. A more specific variable could be how much caffine each participant is given and what time are they given it.
