Along with his white beard, see if this famed psychologist's face rings a bell. The pioneer of "classic conditioning," who is he?

Russian physiologist Ivan Pavlov's famous experiment with salivating dogs was a groundbreaking look at the way classical conditioning works. He referred to his boundless energy as "the instinct for research". He had a good instinct for facial hair too.

Asked by Tom Cohen · Last updated 5 years ago · 1K views