topic is usually called "interesting," but upon analysis
it seems that this means that for one of the above reasons it develops
or changes and therefore holds the attention. This duration of attention
will vary in length from a few seconds to hours. The child who is given
a problem which means almost nothing, which presents a blank wall when
he tries to attend to it, which offers no suggestions for solution, is
an illustration of the first. Attention to such a problem is impossible;
his attention must wander. The genius who, working with his favorite
subject, finds a multitude of trains of thought called up by each idea,
and who therefore spends hours on one topic with no vacillation of
attention, is an illustration of the second.

Attention has been classified according to the kind of feeling which
accompanies the activity. Sometimes attention comes spontaneously,
freely, and the emotional tone is that accompanying successful activity.
On the other hand, sometimes it has to be forced and is accompanied by
feelings of strain and annoyance. The first type is called Free[2]
attention; the second is Forced attention.

Free attention is given when the object of attention satisfies a need;
when the situation attended to provides the necessary material for some
self-activity. The activity of the individual at that second needs
something that the situation in question gives, and hence free,
spontaneous attention results. Forced attention is given when there is a
lack of just such feeling of need in connection with the object of
attention. It does not satisfy the individual--it is distinct from his
desires at the time. He attends only because of fear of the results if
he does not, and hence the condition is one of strain. All play takes
free attention. Work which holds the worker because it is satisfying
also takes free attention. Work which has in it the element of drudgery
needs forced attention. The girl making clothes for her doll, the boy
building his shack in the woods, the inventor working over his machine,
the student absorbed in his history lesson,--all these are freely
attending to the thing in hand. The girl running her seam and hating it,
the, boy building the chicken coop while wishing to be at the ball game,
the inventor working over his machine when his thoughts and desires are
with his sick wife, the student trying to study his history when the
debate in the civics club is filling his mind,--these are cases whe