Validity of Ergo graph as Measurer of Work Capacity 31 



The averages for the right hand of B. show no practice gain ; 

 figures are 1934 in first period and 1929.6 in second period. The 

 left, however, has lost during the period of work quite consid- 

 erably, as shown by the average for the first four records, 1784, 

 when compared with the average for the last four, 1663. The 

 knuckle was inflamed through the imperfect fit of the mask, 

 which made it impossible to continue the experiment further. 

 This inflammation of the knuckle is due to lack of inurement, for 

 later the knuckle recovered completely. This, too, may account 

 for the fact that no gain in practice was made by the left hand. 

 The left hand of M., however, shows a considerable practice gain 

 in its second period of work over the first, the figures being 1799 

 and 2067, and the right hand, with some fluctuations, gains stead- 

 ily in practice effect as shown by the averages for first four rec- 

 ords, 1864.3, compared with average of the last four 2207. The 

 results are therefore inconclusive. Neither reagent was suffi- 

 ciently practiced to insure that degree of habituation which seems 

 to be necessary to get uniform results. The difficulty lies in the 

 fact that if the practice by one hand be suspended long enough to 

 establish a clear gain by the other, the first will lose so much in 

 habituation that the records afterwards will be affected by this 

 loss. A sufficient number of records from which to get a good 

 average can not be taken without inducing a condition of muscle 

 soreness that is prejudicial to the best results. The total results, 

 then, of all our observations upon vicarious practice would favor 

 the hypothesis that there may be vicarious practice effect which 

 is chiefly in the direction of coordination and rhythm. 



Relative standing of right and left hands. — At the beginning 

 of the experiment the right hands of both reagents, it is to be 

 seen, showed considerable superiority over the left hands. Before 

 the end of the first period of work, the left hand of M. showed a 

 slight advantage over the right. In the second period the right 

 again proved itself superior and maintained the superiority until 

 near the end of the third period, when the left surpassed it and 

 maintained its position for several records after the beginning 

 of the fourth period of work. However, before the experiment 

 was finally completed, the left hand was able to write as great a 



109 



