consciousness; it still has behavior, of a kind."]

The best way of getting a true picture of psychology, and of reaching
an adequate definition of its subject-matter, would be to inspect the
actual work of psychologists, so as to see what kind of knowledge they
are seeking. Such a survey would reveal quite a variety of problems
under process of investigation, some of them practical problems,
others not directly practical.

Varieties of Psychology

Differential psychology.

One line of question that always interests the beginner in psychology
is as to how people differ--how different people act under the same
circumstances--and why; and if we watch the professional
psychologist, we often find him working at just this problem. He tests
a great number of individuals to see how they differ, and tries to
discover on what factors their differences depend, how far on
heredity, how far on environment. The "psychologist" in such a place
as the children's court {3} is a specialist whose duty it is to test
the delinquent children that are brought before the court, with the
special object of measuring the intelligence of each individual child
and of helping in other ways to understand the child's peculiar
conduct and attitude.

The "psychological examiner" in the Army, during the Great War, had the
same general object in view. It was desirable to measure the
intelligence of each recruit as he entered the service, since military
experience had shown that men of low intelligence made poor soldiers,
while those of high intelligence made the best officers and
non-commissioned officers, provided they also possessed good physique
and certain less measureable mental qualifications, such as courage
and leadership.

Applied psychology.

The Army psychologists, like the court psychologist, were engaged in
applying scientific knowledge to the practical problems of life; and
there are many other applications of psychology, to education, to
medicine, to business and other occupations, as well as to the art of
right living. Scientific knowledge enables you to _predict_ and
_control_. Having devised scientific tests for intelligence, you can
predict of a six-year-old boy who tests low, that he will not get much
good from the regular classes in school; and thus you are in a
position to control the education of this boy for his own best
interests. In the Army, it happened during the earlier part of the war
that some companies or