features.
At the first trial the animals in every case performed a
wide variety of acts useless to secure the satisfaction they
were instinctively seeking, whether it was food in a box, or
freedom from confinement in a cage. Upon repeated trials
the act appropriate to securing satisfaction was performed with
increasing elimination of useless acts, and consequent decrease
of the time required to perform the act requisite to secure
food, or freedom, or both, as the case might be. One of Thorndike's
famous cat experiments is best told in his own report:

If we take a box twenty by fifteen by twelve inches, replace its
cover and front side by bars an inch apart, and make in this front
side a door arranged so as to fall open when a wooden button inside
is turned from a vertical to a horizontal position, we shall have means
to observe such [learning by trial and error]. A kitten, three to
six months old, if put in this box when hungry, a bit of fish being
left outside, reacts as follows: It tries to squeeze through between
the bars, claws at the bars, and at loose things in and out of the box,
stretches its paws out between the bars, and bites at its confining
walls. Some one of all these promiscuous clawings, squeezings, and
bitings turns round the wooden button, and the kitten gains freedom
and food. By repeating the experience again and again the animal
gradually comes to omit all the useless clawings, and the like, and to
manifest only the particular impulse (_e.g._, to claw hard at the top of
the button with the paw or to push against one side of it with the
nose) which has resulted successfully. It turns the button around
without delay whenever put in the box. It has formed an association
between the situation _confined in a box with a certain appearance_
and the response of _clawing at a certain part of that box in a certain
definite way_. Popularly speaking, it has learned to open a door by
pressing a button. To the uninitiated observer the behavior of the
six kittens that thus freed themselves from such a box would seem
wonderful and quite unlike their ordinary accomplishments of finding
their way to their food or beds.... A certain situation arouses,
by virtue of accident or more often instinctive equipment, certain
responses. One of these happens to be an act appropriate to secure
freedom. It is stamped in in connection with that situation.[1]

[Footnote 1: Thorndike: _Educational Psychology_, Briefer Course. p.