s every time; we may repeat the whole material again
and again, or we may put in long periods of rest after a few
repetitions; we may frequently recite it from memory and have some one
to prompt us; we may give our attention especially to the meaning of
the words, or merely to the sounds, or we may introduce any number of
similar variations. Now the careful experiment shows that of two such
methods one which appears to us the better and more appropriate in
learning, perhaps even as the easier and more comfortable, may prove
itself the less efficient one in the practical result. The psychology
of learning, which won its success by introducing meaningless
syllables as experimental material, has slowly determined the most
reliable methods for impressing knowledge on memory. Where such
results have once been secured, it would surely be a grave mistake
simply to stick to the methods of so-called common sense and to leave
it to the caprice of the individual teacher to decide what method of
learning he will suggest to his pupils. The best method is always the
only one which should be considered. The psychology of economic work
must aim toward similar goals. We must secure a definite knowledge as
to the methods by which a group of movements can best be learned. We
must understand what value is to be attached to the repetitions and to
the pauses, to the imitations and to the special combinations of
movements, to the exercise in parts of the movements, to the rhythm of
the work, and to many similar influences which may shape the learning
process.

The simplest aspect, that of the mere repetition of the movement, has
frequently been examined by psychophysicists. The real founder of
experimental psychology, Fechner, showed the way; he performed
fatiguing experiments with lifted dumb-bells. Then came the time in
which the laboratories began to make a record of the muscular
activities with the help of the ergograph, an instrument with which
the movements of the arm and the fingers can easily be registered on
the smoked surface of a revolving drum. The subtlest variations of the
activity, the increase and decrease of the psychomotor impulse, the
mental fatigue, can be traced exactly in such graphic records. This
psychomotor side of the process, and not the mere muscle activity as
such, is indeed the essential factor which should interest us. The
results of exercise are a training of the central apparatus of the
brain and not of the m