Robert Yerkes vs Robert M. Yerkes

Robert Yerkes and Robert M. Yerkes both are nouns.

Word	Noun	Adjective	Verb	Adverb
Robert Yerkes	Yes	No	No	No
Robert M. Yerkes	Yes	No	No	No

As nouns, Robert Yerkes and Robert M. Yerkes are synonyms defined as:

Robert Yerkes and Robert M. Yerkes: United States psychologist who studied the intelligence of primates (1876-1956)

Other synonyms of Robert Yerkes include Robert Mearns Yerkes, Yerkes.

Robert Yerkes (noun)	Robert M. Yerkes (noun)
United States psychologist who studied the intelligence of primates (1876-1956)	United States psychologist who studied the intelligence of primates (1876-1956)