. But we must not overlook the essential difference between
this so-called thought-reading on the part of animals and that which is
done by man. The human thought-reader can interpret movements, for he is
familiar with the ideas which are their source. Thus when at the second
tap, I notice a very slight jerk of the subject's head, and a stronger
one at the fifth tap, I infer that he thought of the problem 2+3=5.
While the experimenter thus cannot be said to read thoughts, he still
infers them. The animal, on the other hand, we may be reasonably sure,
draws no such inferences. In its conscious life it remains ever on the
sensory level. If we could ask Hans about it, he would probably answer:
"As soon as my master stoops forward, I begin to tap; as soon as he
moves, I stop. The thing which induces me to act thus is the carrot
which is given me; what it is that induces my master to make his
movements, I do not know."--It is therefore erroneous to believe that
animals require the power of abstract thinking in order to utilize the
signs which are consciously or unconsciously given them, as is argued by
Goldbeck[68] when he says with reference to the training for visual
signs, which we have already mentioned before: "There the dog has
consciously interpreted the visual impression in terms of the conclusion
that he is expected to bring forth the leaf indicated." Nor was there
any justification for the critic who thought he could put the essence of
the report of December, given in Supplement IV, into the following
words: "He (Hans) showed that he has the power of attention, can draw
logical conclusions, and can communicate the result of his
thinking,--and all this independently." Yet none of this had been
asserted. The whole thing may be explained satisfactorily by means of a
process of simple association established between the signs observed in
the master and certain reactions on the part of the horse. The fact that
the movements made were so exquisitely minute does not change the matter
in the least. Such signs call for a high degree of sensory keenness and
great concentration of attention, but by no means an "extremely high
intelligence."

[Footnote AD: An illustration is given by Babinet[66] concerning the
horse of an English lord. Mr. Burkhardt-Foottit, also, that
excellent trainer, who has been master for more than forty of the
most highly-trained horses, tells us that while sitting on a
well-managed