experience of a number of practical men, who have had much to do
with horses and yet achieved but very modest success with Hans, goes to
show that it is not always the lack of sufficient authoritativeness,
mentioned under heading 1 that is the sole cause of failure, as has been
claimed so often. That the horse was, to a certain degree, influenced by
this element of authority is shown, however, by the following incident.
A certain gentleman, when alone in the courtyard with Hans, received
responses only so long as I (concealed in the barn) kept the barn-door
open just a little, so that my presence could be known to the horse. As
soon as I closed the door, Hans refused to respond to the gentleman.
Those who possessed sufficient power of concentration and the requisite
motor tendency--the two characteristics mentioned under 1 and 2
above,--were able to obtain responses from the horse without any
previous practice. Practice merely effected a more economic distribution
of attention, so that the larger numbers especially were more successful
as a result (pages 68 and 89). Those who were lacking in either of the
characteristics mentioned under 2 and 3 would not be aided even by the
greatest amount of practice, as is shown by the case mentioned in
Supplement III (page 255).--That many individuals were at first
successful but were later unable to get any successful responses, is to
be accounted for by the fact that the power of concentration, at first
present, later rapidly disappeared. This temporary increase in the power
of doing mental work was first investigated experimentally by Rivers and
Kraepelin,[95] and was called by them "Antrieb" and aptly likened to the
first pull of a team of horses in starting off. This, too, explains an
experience which befell a number of the horse's visitors, who later
described it to me. Wishing to utilize a momentary absence of Mr. von
Osten, they excitedly put a hasty question to Hans, and with amazing
regularity received correct responses.--Besides Mr. von Osten, Mr.
Schillings and myself, not many were always able to induce Hans to bring
the colored cloths or to execute the head movements. It was easy, on the
other hand, to get him to nod. Therefore there was some truth in Mr. von
Osten's assertion, that Hans would be unable to answer a difficult
question if he had not previously indicated by means of a nod that he
had grasped its import. Those who were not concentrating sufficiently,
would n