PSYCHOLOGICAL MEASUREMENTS. 



591 



Squad A 

 Squad B 



efforts with the result of quick development of fatigue or conditions 

 which produce pain. Squad A made better averages in their first two 

 sessions than in any of the subsequent periods, and the variability- 

 tends to be largest; there would seem to be some connection between 

 these two factors. The changes in variability with Squad B are not 

 so marked; they were about the same level all the time, with some 

 decrease in the case of evening work particularly. 



In summarizing the effect of the reduced diet on the strength of grip, 

 we have to consider these facts: (1) There are two squads of 10 men 

 each with no apparent reason for believing that the average grip 

 strength of one squad should be much greater than the other under 

 normal conditions. With Squad A on reduced rations, we find a 

 definite difference between 

 the two groups of men. 

 (2) Records taken with 6 

 of the members of Squad 

 A after the reduced-diet 

 period and at a time when 

 it might be considered that 

 the men had returned to 

 approximately normal con- 

 ditions, show, on the aver- 

 age, a strength of grip 

 about 4.5 kg. greater than 

 that demonstrated during 

 the low-diet period. (3) 

 There was a gradual re- 

 duction in the strength of 

 grip with Squad A from 

 the beginning until the last 

 of the experiment. (4) In 

 the 3 weeks' diet period 

 with Squad B there was 

 some reduction below the previous performance. (5) In all the records, 

 the coefficient of variability for individual series of five trials remains 

 quite constant at about 4 per cent, thus indicating uniformity of effort 

 in the test. It would therefore seem that the strength of grip was defi- 

 nitely lowered by the reduced diet regime. In the absence of normal 

 measurements for Squad A previous to the period of diet and for half 

 of the men subsequent to the experiment, it is impossible to say how 

 large the reduction may be. It is not unreasonable to believe that it 

 averaged about 4 kg. in 50, which amounted to approximately an 8 

 per cent reduction in strength as exhibited in this test. 



Fig. 



110. — Variability in the average strength of 

 grip at morning sessions. 



R and L designate values for right and left hands. 



