t
bangs on the floor, and keeping this up time after time), and this
element can still be detected in various forms of joke that are
effective mirth-provokers in the adult. But why the child should laugh
when tickled, at the same time trying to escape, is a poser. Many
students of humor have subscribed to the theory that what makes us
laugh is a sudden sense of our own superiority, thus attaching
laughter to the self-assertive instinct, soon to be discussed. The
laugh of victory, the laugh of defiance, the laugh of mockery, the sly
or malicious laugh, support this theory, but can it be stretched to
cover the laugh of good humor, the tickle laugh, or the baby's laugh
in general? That seems very doubtful, and we must admit that we do not
know the essential element in a laughter stimulus. One thing is fairly
certain: that, while laughing is a native response, we learn what to
laugh at, for the most part, just as we learn what to fear.

Fighting.

Hold the new-born infant's arms tightly against its sides, and you
witness a very peculiar reaction: the body stiffens, the breath may be
held till the face is "red with anger"; the child begins to cry and
then to scream; the legs are moved up and down, and the arms, if they
can be got free, make striking or slashing movements. In somewhat
older children, any sort of restraint or interference with free
movement may give a similar picture, except that the motor response is
more efficient, consisting in struggling, striking, kicking, and
biting. It is not so much pain as interference that gives this
reaction. You get it if you take away a toy the child is playing with,
or if you forbid {159} the child to do something he is bent on doing.
In animals, the fighting response is made to restraint, to being
attacked, or to being interfered with in the course of feeding, or
mating, or in the instinctive care of the young. The mother lioness,
or dog or cat or hen, is proverbially dangerous; any interference with
the young leads to an attack by the mother. The human mother is no
exception to this rule. In human adults, the tendency to fight is
awakened by any interference with one's enterprises, by being insulted
or got the better of or in any way set down in one's self-esteem.

In general, the stimulus to fighting is restraint or interference. Let
any reaction-tendency be first aroused and then interfered with, and
pugnacious behavior is the instinctive result.

The stimulus may be a