things", i. e. the overcoming
of psycho-physical inertia, has long been known in the case of man and
has been experimentally determined and called "Anregung" (excitation) by
the psychiatrist, Kraepelin,[22] and his pupil, Amberg.[23] A massing of
errors toward the end of a long series occurred only when the questioner
was fatigued. There was nothing which had to be interpreted as fatigue
or as indisposition on the part of the horse, (except in the few cases
of very large numbers, cf. page 67). To be sure, Mr. von Osten always
offered these two excuses. That they were without warrant is shown by
the fact that Hans, after appearing indisposed or fatigued while working
with one questioner, would nevertheless react promptly and correctly a
moment later for some other experimenter, and furthermore, when working
with me, the number of his correct responses would rise or fall with my
own mental disposition.

Finally, I would here note a rather interesting observation for which I
am indebted to Mr. Schillings and the Count zu Castell. They had
noticed, independently of each other, that the horse would often fail to
react when for any length of time he was given problems dealing with
abstract numbers, even though they were of the simplest kind; but that
he would immediately improve whenever the questions had to do with
concrete objects. They believed that Hans found applied mathematics more
interesting, and that abstract problems, or those which were altogether
too elementary, bored him. The Count zu Castell furthermore noticed that
the responses tended to be more correct as soon as he had the horse
count objects which he, himself, (Castell) could see during the test.
Quite in accord with this is the statement to be found in the report of
the September-Commission, in which we find this note in a discussion of
the arithmetical problems (not involving visible objects), which the
gentlemen already mentioned had given the horse. "The horse responded
with less and less attentiveness and appeared to play with the
questioner." Here again, that was looked for in the animal which should
have been sought in the man. Mr. Schillings was capable of intense, but
not continued concentration and it was he who was bored, and not the
horse. And it was the Count zu Castell and not the horse that found it
necessary to invoke the aid of perceptual objects to bring his
attention to the proper height of concentration.

The reader will see that thus f