novelty wears off,
therefore the progress becomes less marked and the curve shows
fluctuations.

Another characteristic of the learning curve is the presence of the
so-called "plateaus." Plateaus show in the curve as flat, level
stretches during which there has apparently been no progress. The
meaning of these level stretches, and whether or not they can be
entirely done away with in any curve, is a matter of dispute. These
pauses may be necessary for some of the habits to reach a certain degree
of perfection before further progress can be made. However this may be,
there are several minor causes which tend to increase the number of
plateaus and to lengthen the time spent in any one. In the first place
an insecure or an inaccurate foundation must result in an increase of
plateaus. If at the beginning, during the initial spurt, for instance,
the learner is allowed to go so fast that what he learns is not
thoroughly learned, or if he is pushed at a pace that for him makes
thoroughness impossible, plateaus must soon occur in his learning curve.
In the second place a fruitful cause of plateaus is loss of
interest,--monotony. If the learner is not interested, he will not put
forth the energy necessary for continued improvement, and a time of no
progress is the result. The attitude of the learner toward the work is
extremely important, not only in the matter of interest, but in the
further attitude of self-confidence. Discouragement usually results in
hindering progress, whereas confidence tends to increase it. The
psychological explanation of this is very evident. Both lack of interest
in the learning and the presence of discouragement are likely to result
in divided attention and that, as has already been shown, results in
unsatisfactory work. A third cause for plateaus is physiological. Not
only must the learner be in the right attitude towards the work, but he
must feel physically "fit." There seem to be certain physiological
rhythms that may disturb the learning process whose cause cannot be
directly determined, but generally the feeling of unfitness can be
traced to a simple cause,--such as physical illness, loss of sleep,
exercise, or food, or undue emotional strain.

The older psychology has left an impression that improvement in any
function is limited both as to amount and as to the period during which
it must be attained. The physiological limit of improvement has been
thought of as one which was rather easily re