aration. An animal is placed before a
row of three food boxes, all looking just alike, two of them, however,
being locked while the third is unlocked. Sometimes one is unlocked
and sometimes another, and the one which at any time is unlocked is
designated by an electric bulb lighted above the door. The animal is
first trained to go to whichever box shows the light; he always gets
food from the lighted box. When he has thoroughly learned to respond
in this way, the "delayed reaction" experiment begins. Now the animal
is held while the light is burning, and only released a certain time
after the light is out, and the question is whether, after this delay,
he will still follow the signal and go straight to the right door. It
is found that he will do so, provided the delay is not too long--how
long depends on the animal. With rats the delay cannot exceed 5
seconds, with cats it can reach 18 {77} seconds, with dogs 1 to 3
minutes, with children (in a similar test) it increased from 20
seconds at the age of fifteen months to 50 seconds at two and a half
years, and to 20 minutes or more at the age of five years.

Rats and cats, in this experiment, need to keep their heads or bodies
turned towards the designated box during the interval between the
signal and the release; or else lose their orientation. Some dogs,
however, and children generally, can shift their position and still,
through some inner orientation, react correctly when released. The
point of the experiment is that the light signal puts the animal or
child into a state tending towards a certain result, and that, when
that result is not immediately attainable, the state persists for a
time and produces results a little later.

Preparatory Reactions

In the delayed reaction, the inner orientation does little during the
interval before the final reaction, except to maintain a readiness for
making that reaction; but often "preparatory reactions" occur before
the final reaction can take place. Suppose you whistle for your dog
when he is some distance off and out of sight. You give one loud
whistle and wait. Presently the dog swings around the corner and
dashes up to you. Now, what kept the dog running towards you after
your whistle had ceased and before he caught sight of you? Evidently
he was directed towards the end-result of reaching you, and this
directing tendency governed his movements during the process. He made
many preparatory reactions on the way to his f