“聪明汉斯”现象如何塑造了现代实验科学

At the dawn of the 20th century, prominent scientists and philosophers—including Nobel laureate J.J. Thomson and philosopher C.D. Broad—devoted significant attention to the study of psychic phenomena. This intellectual curiosity extended beyond human mediums to include animals, with researchers investigating claims of horses and dogs possessing mathematical abilities or the power of telepathy.

Among the most notable cases were Rolf, a dog in Germany allegedly capable of spelling out sentences, and Lady Wonder, a horse reported to solve arithmetic problems. Philosopher F.C.S. Schiller, a member of the Society for Psychical Research, was a vocal proponent of these investigations, even suggesting that such animals could communicate complex thoughts. While some researchers argued these animals possessed hidden intellect, others, such as neuroscientist Vladimir Bechtereev, proposed that telepathic communication between owners and animals explained the behavior.

The scrutiny reached a turning point with Clever Hans, a horse in Germany that drew massive crowds for its supposed mathematical prowess. Psychologist Carl Stumpf and his assistant, Oskar Pfungst, conducted a rigorous investigation into the horse's abilities. Pfungst discovered that Hans only answered correctly when his owner was present and aware of the answer, revealing that the horse was reacting to subtle, involuntary physical cues from the human. This finding became known as the "Clever Hans effect," a foundational concept in psychology describing how an experimenter’s expectations can unintentionally influence a subject's performance.

While the "psychical research" of the era was eventually largely discredited, the rigorous attempts to test these claims left a lasting mark on scientific methodology. The need to eliminate unconscious bias and human influence led to the development of randomization in experimental design. By ensuring that researchers and participants could not influence outcomes through expectation or subtle signaling, these early, unconventional studies helped establish the standards for objective scientific inquiry used today.

Source: The Conversation