ch toward
bright objects checked by the experience of putting its hand
in the flame. Later his tendency to take all the food within
reach may be checked by the looks of scorn which follow that
manifestation of man's original greed, or the punishment and
privation which are correlated with it. Through experience
with punishment and reward, humans may be taught to do
precisely the opposite of what would have been their original
impulse in any given situation, just as the monkey reported
by one experimenter may be taught to go to the top of his
cage whenever a banana has been placed at the bottom.

THE PROLONGED PERIOD OF INFANCY. Probably the most
significant and unique fact of human behavior is the period of
"prolonged infancy" which is characteristic of human beings
alone. Fiske and Butler in particular have stressed the
importance of this human trait. In the lower animals the period
of infancy--that is, the period during which the young are
dependent upon their parents for food, care, and training--is
very short, extending even in the highest form of ape to not
more than three months. This would appear, at first blush,
to be a great advantage possessed by the lower animals.
They come into the world equipped with a variety of tendencies
to act which, within a week, or, as in the case of chickens,
almost immediately after birth, are perfectly adapted to
secure for them food, shelter, and protection. They are
mechanisms from the beginning perfectly adjusted to their
environment.

The human infant, while it is born with a greater number of
instinctive activities than other animals, is able to make little
use of them just as they stand. For years after birth it is
helplessly dependent on others to supply its most elementary
needs. It must be fed, carried, and sheltered; it cannot by
itself even reach for an object, and it cannot for nearly two
years after birth specifically communicate its wants to other
people. But this comparatively long helplessness of the human
infant is perhaps the chief source of human progress.

The human baby, because it can do so little at the start,
because it has so many tendencies to act and has them all so
plastic, undeveloped, and modifiable, has to a unique degree
the capacity to learn. This means that it can profit by the
experience of others and adjust itself to a great variety and
complexity of situations. The chicken or the bird can do a
limited number of things perfectly, but it