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 large influence which training has on concentration and the great improvement that can be made.  It is true that few people do show much concentration of attention when they wish.  This is true of adults as well as of children.  They have formed habits of working at half speed, with little concentration and no real absorption in the topic.  This method of work is both wasteful of time and energy and injurious to the mental stability and development of the individual.  Half-speed work due to lack of concentration often means that a student will stay with a topic and fuss over it for hours instead of working hard and then dropping it.  Teachers often do this sort of thing with their school work.  Not only are the results less satisfactory, because the individual never gets deeply enough into the topic to really get what is there, but the effect on him is bad.  It is like “constant dripping wears away the stone.”  Children must be taught to “work when they work and play when they play,” if they are to have habits of concentration as adults.

The length of time which it is possible to attend to the same object or idea may be reckoned in seconds.  It is impossible to hold the attention on an object for any appreciable length of time.  In order to hold the attention the object must change.  The simple experiment of trying to pay attention to a blot of ink or the idea of bravery proves that change is necessary if the attention is not to wander.  What happens is that either the attention goes to something else, or that you begin thinking about the