quire in the case of psychophysical
experiments conducted under regular laboratory conditions. All sorts of
difficulties had to be overcome: unfavorable weather, the crowds of
curious ones, certain peculiarities of the horse--such as shying
whenever the wind rippled the canvas of the tent--and last but not
least, the idiosyncrasies of Mr. von Osten who repeatedly attempted to
interrupt the progress of the experiments.

Since it was evident that different kinds of processes were involved in
solving the problems and since the solutions would be indicated by
tapping, or by movements of the head, or by walking over to the object
to be designated, the results of these three sets of experiments have
been grouped under three corresponding heads.

_I. Problems solved by tapping_

The following tests were made in which the method was such that when the
problem was presented to the horse, the correct solution was known to
none of those present, least of all to the questioner. This method we
shall designate in the following report as "procedure without knowledge"
whereas we shall call the method in which the answer was known to the
questioner, "procedure with knowledge".

In order to discover if the horse could read numbers, a series of cards
on which numerals were blazoned, were exposed to the horse's view in
such a way that none of those present was able to see them, and the
horse was asked to tap the numbers as they were shown. This experiment
was repeated at different times and in all there were 49 tests in which
procedure was without knowledge, and 42 in which procedure was with
knowledge. In the case of the former there were 8% correct responses,
whereas in the case of the latter 98% of the answers were right. As an
example of the course which the series tended to take, we insert the
following, in which Mr. von Osten himself acted as questioner.

Method. No. exposed. No. tapped.

Without knowledge 8 14
With " 8 8
Without " 4 8
With " 4 4
Without " 7 9
With " 7 7
Without " 10 17
With " 10 10
Without " 3 9
With " 3 3 etc.

Whenever the questioner knew the solution, nearl