involved no intellectual process, for if that were
the case, then the responses in the tests with the placards would have
been very much more difficult, for they would have involved the ability
to read, whereas the tests with the colored cloths demanded only that a
few names be remembered. Nevertheless, the horse was as unsuccessful in
tests of one kind as he was in those of the other,--even when Mr. von
Osten acted as questioner. (50% failures in 78 placard tests; 46%
failures in 103 color tests.)

The fact that commands which were purposely enunciated poorly, or else
not spoken at all, were executed with just as much accuracy as those
given aloud, strengthened us in our supposition. On one occasion I
placed a blank placard with the others. When I ordered him to approach
_tabula rasa_, he invariably went to the right one. The following
illustrates how he fulfilled quite nonsensical commands. A series of
blue and green cloths lay upon the ground. Being asked where the black,
the orange, and the yellow cloths lay, Hans shook his head
energetically, i. e. they were not there. And yet, upon being asked to
bring them in the order named, he regularly brought one of the blue
ones.

All this goes to show that Hans did not know the names of the colors (to
say nothing of the symbols on the placards). It was plain that here
also, as in all the other cases, he was controlled by signs made by the
questioner, the nature of which I soon discovered. Standing erect, Mr.
von Osten always turned head and trunk in the direction of the cloth or
placard desired. Hans, keeping his eye on his master, would proceed in
that direction. Even after he had already started out, thanks to his
large visual field one could control his direction by turning slightly
more to the right or to the left. If, however, he had already arrived at
the row of placards or cloths, this method ceased to be effective, for
then he could no longer see the experimenter. It made no difference
whether the cloths lay on the ground, or were suspended, like the
placards.

The following fact justifies the conclusion that the bodily attitude of
the questioner was the effective signal. The more numerous the cloths,
or the nearer they were placed together, the more difficult one would
expect it to be for the horse to select the one indicated by the
experimenter. Such was indeed the case, for the number of errors
increased with the number of cloths presented.

But no matter ho