In the experiment on subliminal perception, students listened to tapes they thought would enhance their memory or self-esteem for five weeks. At the end of the experiment:
a) Students who thought they had a memory tape believed their memories had improved; but, in fact, there was no improvement.
b) Self-esteem, but not memory, improved.
c) Memory, but not self-esteem, improved.
d) Both self-esteem and memory improved over the course of the experiment.