r.
The child who in the primary can be given only one thing to look for
when he goes on his excursion may grow into the youth who can carry half
a dozen different questions in his mind to which he is looking for
answers.

By concentration of attention is meant the depth of the attention, and
this is measured by the ease with which a person's attention can be
called off the topic with which he is concerned. The concentration may
be so great that the individual is oblivious to all that goes on about
him. He may forget engagements and meals because of his absorption.
Sometimes even physical pain is not strong enough to distract attention.
On the other hand, the concentration may be so slight that every passing
sense impression, every irrelevant association called up by the topic,
takes the attention away from the subject. The depth of concentration
depends upon four factors. Certain mental and physical conditions have a
great deal to do with the concentration of attention, and these will be
discussed later. Individual differences also account for the presence or
absence of power of concentration--some people concentrate naturally,
others never get very deeply into any topic. Maturity is another factor
that is influential. A little child cannot have great concentration,
simply because he has not had experience enough to give him many
associations with which to work. His attention is easily distracted.
Although apparently absorbed in play, he hears what goes on about him
and notices many things which adults suppose he does not see. This same
lack of power shows itself in any one's attention when a new subject is
taken up if he has few associations with it. Of course this means that
other things being equal the older one is, up to maturity at least, the
greater one's power of concentration. Little children have very little
power, adolescents a great deal, but it is the adult who excels in
concentration. Although this is true, the fourth factor, that of
training in concentration, does much toward increasing the power before
full maturity is reached. One can learn to concentrate just as he can
learn to do anything else. Habits of concentration, of ignoring
distinctions and interruptions, of putting all one's power into the work
in hand, are just as possible as habits of neatness. The laws of habit
formation apply in the field of attention just as truly as in every
other field of mental life. Laboratory experiments prove the lar