Hermann Ebbinghaus, the First Researcher to Study Memory Experimentally, Used

Hermann Ebbinghaus, the first researcher to study memory experimentally, used _______ instead of words to study memory because ________.

A) nonsense syllables; he didn't want his memory to be biased for some items more than others as a result of his own personal experience with those words
B) musical notes; he didn't want his memory to be biased by his own personal experience with those words
C) nonsense syllables; he wanted to see what meaning would be attached to these syllables by his own imagination
D) pictures; he didn't want his memory to be biased by his own personal experience with those words