120 



THE ACQUISITION OF SKILL IN ARCHERY. 



EFFECT OF THE DISTRIBUTION OF PRACTICE. 



The group shooting 5 shots daily was organized first and their practice 

 continued for about 2 weeks before the 20- and 40-shot groups started. Their 

 practice extended, altogether, from June 22 until September 20. Practice 

 could not be carried out on Sunday and comparable records of 31)0 shots were 

 obtained from the 12 weeks' i)ractice. 



The 20- and 40-shot groups were organized at the same time and their 

 practice was continued for 4 weeks, giving records of approximatel.y 400 shots 

 for each subject in the 20-shot group and 800 for each in the other group. 

 Comparisons have been made only of the rate of improvement, measured in 

 various ways, in the amount of practice represented by 360 shots. A more 

 certain method of comparing the groups would have been perhajis to continue 

 the practice of each group until a given degree of accuracy was attained and 

 then comjiaring the amount of practice necessary to reach this stage, as was 

 done by Ulrich in his study of the rat, but this method is practicable only 

 when the final accuracy selected is near the limit of improvement, and the 

 time requirements for such an experiment could not be met. 



For purposes of comparison the records of the groups have been averaged 

 in series of successive 20 shots and the curves in figure 19 have been plotted 

 upon the basis of these averages, which are given in table 39. The daily aver- 

 ages are disregarded in this treatment of the data, which consist of averages 

 for like amounts of practice. The records of the 12- and 60-shot groups are 

 included for comparison with these others, although, as has been shown, these 

 groups are not strictly comparable with the remainder. 



Table 39. — Ai'erages of successive groups of 20 shots for the groups of subjects compared. 

 [Fi^viri--: arc in iiiolin.s from the center of tl\e l)uUs-eyc.I 



.\rrovvs looseil per ilay. 



.56.9 

 40.1 



35.2 

 43.1 

 39.6 

 40.7 

 40.8 

 35.4 



.5S,4 

 49.2 

 45.3 

 43.6 

 40.9 

 38.8 

 43.6 

 40.8 

 36 . 2 



44.7 

 40.6 

 41.8 

 42.4 

 36.9 

 39.1 

 38.4 



48.9 

 44 4 

 39.7 

 36.2 

 35.7 

 .36.6 

 33.9 

 32.8 

 .32.1 



75 . 4 

 66.1 

 51.5 

 54.0 

 60.1 

 50.7 

 50.7 

 48.7 

 55.9 



loo.-4eJ per rla^ 



30.9 

 27.1 

 30.7 

 25.6 

 28.9 

 35.7 

 31.4 

 27.1 



40 . 1) 

 45.4 

 32.9 

 36.1 

 36.7 

 38.3 

 35.3 

 .38.6 

 44 5 



33 . 1 

 29 6 

 32.2 

 30.6 

 29.1 

 31.3 

 32.6 

 29.1 

 .32.7 



48.9 

 46.9 



46.0 

 40.2 

 44.3 



From inspection of the curves in figure 19 it appears that the .5-shot group is 

 considerably superior to the others in final accuracy and in the amount of 

 improvement, possibly excepting the 12-shot group. The superiority of this 

 group is really somewhat greater than is apparent from the curve, for the sud- 

 den loss in accuracy coming at the 320th shot is the result of a few days of 

 extremely cold weather, which stiffened the fingers of the subjects and made 

 accurate shooting impossible. 



The 60-shot group shows a greater average accuracy but less improvement 

 than the 5-shot group. The r2-shot group shows a much lower accuracy than 



