118 THE ACQUISITION OF SKILL IN ARCHERY. 



group. The second, third, etc., shots were averaged in the same way. The 

 differences betAveen the average of the first and fifth shots gives a rough 

 measure of the improvement during practice. In the same way averages were 

 obtained for the 20- and 40-shot groups, but the averages of successive 5 shots 

 instead of single shots were taken, making the average improvement shown a 

 little too small in comparison with that of the 5-shot group. These were then 

 reduced to terms of average improvement during 5 shots loosed in rapid 

 succession. The averages are 1.5 inches for the 5-shot group; 1.5 inches for 

 the 20-shot group; and a negative improvement of 0.2 inch for the 40-shot 

 group. The full data are given in table 38. Little more can be deduced 

 from the results than that fatigue is much more severe after 40 shots than 

 after 20, in the former case obscuring any progress made or perhaps pre- 

 venting progress (see p. 126). 



The question of improvement during periods of no practice is closely related 

 to that of the effect of fatigue in obscuring the improvement during practice. 

 The data have not been analyzed carefully for the improvement during the 

 24-hour periods of rest, but the effects of some 48-hour periods of rest have 

 been examined. In the 5-shot group there was a decided loss during these 

 periods in the case of 3 of the 4 subjects. The fourth showed a slight gain. 

 The absolute amount of gain was 



+ 1.5 -5.0 -3.5 -3.2 



With the results not obscured by fatigue there is a decided loss after practice 

 is stopped. 



For the 40-shot group the average gains during 48-hour periods without 

 practice were 



-0.5 -0.7 +2.5 +5.5 



The record of the individual making the greatest progress during this period is 

 given in figure 18. The solid lines of the figure connect the averages of the 

 first and second 20 shots loosed daily. The dotted lines represent the inter- 

 vals of no practice. The effects of fatigue are very pronounced in this case. 

 Other individuals of this group show such effects to a less marked degree. 



40 







/'/W-VsA _ A 



V 



'^"\ /-~A / \ 



V V ^~ \ 



, v \ 



100 200 300 400 GOO 600 700 800 



FIG. 18. Effects of fatigue. Learning eurve of one individual in 40-shot group is shown, 

 plotted for successive groups of 20 shots. Solid lines show improvement during prac- 

 tice; dotted lines, improvement from one day to next. 



The question of the part played by imitation in the improvement of the 

 subjects is an interesting one. They watched each other's practice and the 

 practice of the experimenter during the greater part of the experiment. From 

 the different methods of aiming employed by different subjects it seems that 



