l Psychology.= Educational psychology is that division of
psychology which undertakes to discover those aspects of human nature
most closely related to education. These are (1) the original nature of
the child--what it is and how it can be modified; (2) the problem of
acquiring and organizing experience--habit-formation, memory, thinking,
and the various factors related to these processes. There are many
subordinate problems, such as the problem of individual differences and
their bearing on the education of subnormal and supernormal children.
Educational psychology is not, then, merely the application of
psychology to education. It is a distinct science in itself, and its aim
is the solving of those educational problems which for their solution
depend upon a knowledge of the nature of the child.

=The Method of Psychology.= We have enumerated the various problems of
psychology, now how are they solved? The method of psychology is the
same as that of all other sciences; namely, the method of observation
and experiment. We learn human nature by observing how human beings act
in all the various circumstances of life. We learn about the human mind
by observing our own mind. We learn that we _see_ under certain
objective conditions, _hear_ under certain objective conditions,
_taste_, _smell_, _feel cold_ and _warm_ under certain objective
conditions. In the case of ourselves, we can know both our _actions_ and
our _mind_. In the case of others, we can know only their _actions_, and
must infer their mental states from our own in similar circumstances.
With certain restrictions and precautions this inference is legitimate.

We said the method of psychology is that of observation and experiment.
The experiment is observation still, but observation subjected to exact
methodical procedure. In a psychological experiment we set out to
provide the necessary conditions, eliminating some and supplying others
according to our object. The experiment has certain advantages. It
enables us to isolate the phenomena to be studied, it enables us to vary
the circumstances and conditions to suit our purposes, it enables us to
repeat the observation as often as we like, and it enables us to measure
exactly the factors of the phenomena studied.

=A Psychological Experiment.= Let us illustrate psychological method by a
typical experiment. Suppose we wish to measure the individual
differences among the members of a class with respect to a certain