can send or receive with accuracy per minute. In learning telegraphy, progress is rapid for a few weeks and then follow many weeks of less rapid improvement. Figure 4 presents the <p 229 history of a student of telegraphy who was devoting all his time to sending and receiving messages. His speed was measured once a week from his first week to the time when he
{illust. caption = FIG. 4.}
could be classed as a fully accomplished operator. By the twentieth week this operator could receive less than 70 letters a minute, although he could send over 120 letters a minute. At the end of the fortieth week he had <p 230> reached a speed of sending which he would probably never greatly excel even though his speed was far below that attained by many operators. The receiving rate might possibly rise either slowly or rapidly until it equaled or exceeded the sending rate.—BRYAN & HARTER, ``Studies in the Physiology and Psychology of the Telegraphic Language,'' Psychological Review, Vol. IV, p. 49.
There are certain forms of learning and practice which do not readily admit of quantitative determinations. Nevertheless very successful attempts have been made even in the most difficult realms of learning. A beginner with the Russian language spent 30 minutes daily in industrious study and then was tested for 15 minutes as to the number of Russian words he could translate. Figure 5 shows diagrammatically the results of the experiment. Thus on the thirteenth day 22 words were translated; on the fiftieth day 45 words. Improvement was rather rapid until the nineteenth day, and then followed a slump till the forty-sixth day. Improvement was very ir- <p 231> regular.—SWIFT, E. J., ``Mind in the Making,'' p. 198.
These five figures are typical of nearly all
{illust. caption = FIG. 5.}
practice, or learning, curves. They depict the rate at which the beginner increases his efficiency. In every case we discover very great <p 232> fluctuations. On one day or at one moment there is a sudden phenomenal improvement. The next day or even the next moment the increase may be lost and a return made to a lower stage of efficiency.
There are certain forms of skill which cannot be acquired rapidly in the beginning. In such instances a period of time is necessary in which to ``warm up'' or in which to acquire the knack of the operation or the necessary degree of familiarity and self-confidence before improvement becomes possible. This is true particularly in the ``breaking in'' of new operators on large machines like steam hammers, cranes, and the like, where the mass and power of the machine awes the new man, even though he has had experience with smaller units of some kind. It applies also to new inspectors of mechanical parts and completed products in factories—especially where the factor of judgment enters into the operation. Such instances are exceptions, however, and differ from those cited only in having a period of slow advance preliminary to the rapid progress. <p 233>
Apparently, improvement should be continuous until the learner has entered into the class of experts or has reached his possible maximum. As a matter of fact the curve which expresses his advance towards efficiency never rises steadily from a low degree to a high one. Periods of improvement are universally followed by stages of stagnation or retrogression. These periods of little or no improvement following periods of rapid improvement are called ``plateaus'' and are found in the experience of all who are acquiring skill in any line.
These plateaus are not all due to the same cause.