Free Broca's Brain by Carl Sagan Page A

it genuine. Hans would reply to mathematical problems put to him with coded taps of his foreleg, and would answer nonmathematical questions by nodding his head up and down or shaking it side to side in the conventional Western way. For example, someone would say, “Hans, how much is twice the square root of nine, less one?” After a moment’s pause Hans would dutifully raise his right foreleg and tap five times. Was Moscow the capital of Russia? Head shake. How about St. Petersburg? Nod.
    The Prussian Academy of Sciences sent a commission, headed by Oskar Pfungst, to take a closer look; Osten, who believed fervently in Hans’s powers, welcomed the inquiry. Pfungst noticed a number of interesting regularities. Sometimes, the more difficult the question, the longer it took Hans to answer; or when Osten did not know the answer, Hans exhibited a comparable ignorance; or when Osten was out of the room, or when the horse was blindfolded, no correct answers were forthcoming. But other times Hans would get the right answer in a strange place, surrounded by skeptics, with Osten not only out of the room, but out of town.The solution eventually became clear. When a mathematical question was put to Hans, Osten would become slightly tense, for fear Hans would make too few taps. When Hans, however, reached the correct number of taps, Osten unconsciously and imperceptibly nodded or relaxed—imperceptibly to virtually all human observers, but not to Hans, who was rewarded with a sugar cube for correct answers. Even teams of skeptics would watch Hans’s foot as soon as the question was put and make gestural or postural responses when the horse reached the right answer. Hans was totally ignorant of mathematics, but very sensitive to unconscious nonverbal cues. Similar signs were unknowingly transmitted to the horse when verbal questions were posed. Clever Hans was aptly named; he was a horse who had conditioned one human being and discovered that other human beings he had never before met would provide him the needed cues. But despite the unambiguous nature of Pfungst’s evidence, similar stories of counting, reading and politically sage horses, pigs and geese have continued to plague the gullible of many nations. *

PRECOGNITIVE DREAMS
     
    ONE OF THE MOST striking apparent instances of extrasensory perception is the precognitive experience, when a person has a compelling perception of an imminent disaster, the death of a loved one, or a communication from a long-lost friend, and the predicted event then transpires. Many who have had such experiences reportthat the emotional intensity of the precognition and its subsequent verification provide an overpowering sense of contact with another realm of reality. I have had such an experience myself. Many years ago I awoke in the dead of night in a cold sweat, with the certain knowledge that a close relative had suddenly died. I was so gripped with the haunting intensity of the experience that I was afraid to place a long-distance phone call, for fear that the relative would trip over the telephone cord (or something) and make the experience a self-fulfilling prophecy. In fact, the relative is alive and well, and whatever psychological roots the experience may have, it was not a reflection of an imminent event in the real world.
    However, suppose the relative had in fact died that night. You would have had a difficult time convincing me that it was merely coincidence. But it is easy to calculate that if each American has such a premonitory experience a few times in his lifetime, the actuarial statistics alone will produce a few
apparent
precognitive events somewhere in America each year. We can calculate that this must occur fairly frequently, but to the rare person who dreams of disaster, followed rapidly by its realization, it is uncanny and awesome. Such a coincidence must happen to
someone
every few months. But those who experience a correct precognition understandably resist its