author
Oskar Pfungst
1874–1933
Best remembered for solving the mystery of Clever Hans, this German psychologist helped show how easily animals—and people—can pick up on subtle human cues. His work became a lasting lesson in careful observation and experimental method.
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About the author
Oskar Pfungst was a German comparative biologist and psychologist, born on April 21, 1874, in Frankfurt am Main. He is most closely associated with the famous case of Clever Hans, the horse that seemed able to solve arithmetic problems and answer questions by tapping its hoof.
Working as a volunteer assistant in Carl Stumpf’s laboratory in Berlin, Pfungst investigated the horse and showed that Hans was not actually calculating. Instead, the animal was responding to tiny, unintentional signals from the people around him. That finding made Pfungst’s name an important part of the history of psychology, especially in discussions of observer bias, animal cognition, and what later became known as the Clever Hans effect.
He published his findings in 1907, and the case is still widely discussed because it changed how researchers think about experiments involving both animals and humans. Some sources list his death year differently, but the biographical sources found here identify him as having died on August 14, 1932.