e most complicated questions. For instance, it apparently not
only solved such problems as 3 times 4 by tapping 12 times, and 6 times
3 by tapping 18 times, but even extracted square roots, distinguished
between concords and discords, also between ten different colors, and
was able to recognize the photographs of people; altogether, Clever Hans
was supposed to be at that time about upon a level with fifth-form boys
(the fifth form is the lowest form but one in a German gymnasium). After
investigating the matter, Stumpf and the members of his committee drew
up the following conjoint report, according to which only one of two
things was possible--either the horse could think and calculate
independently, or else he was under telepathic, perhaps occult,
influence:

The undersigned met together to decide whether there was any
trickery in the performance given by Herr v. Osten with his
horse, i.e., whether the latter was helped or influenced
intentionally. As the result of the exhaustive tests employed,
they have come to the unanimous conclusion that, apart from the
personal character of Herr v. Osten, with which most of them
were well acquainted, the precautions taken during the
investigation altogether precluded any such assumption.
Notwithstanding the most careful observation, they were well
unable to detect any gestures, movements, or other intimations
that might serve as signs to the horse. To exclude the possible
influence of involuntary movements on the part of spectators, a
series of experiments was carried out solely in the presence of
Herr Busch, councilor of commissions. In some of these
experiments, tricks of the kind usually employed by trainers
were, in his judgment as an expert, excluded. Another series of
experiments was so arranged that Herr v. Osten himself could
not know the answer to the question he was putting to the
horse. From previous personal observations, moreover, the
majority of the undersigned knew of numerous individual cases
in which other persons had received correct answers in the
momentary absence of Herr v. Osten and Herr Schillings. These
cases also included some in which the questioner was either
ignorant of the solution or only had an erroneous notion of
what it should be. Finally, some of the undersigned have a
personal knowledge of Herr v. Osten's method, wh