PSYCHOLOGICAL MEASUREMENTS. 



599 



47.9 and 50.6 cr respectively. These values correspond very nearly with 

 the 244 a, and coefficient of variability of 19 per cent for the normal 

 series of 1917. The averages for Squads A and B are about 10 c less, 

 due, no doubt, to our method of dealing with the preliminary long re- 

 actions just mentioned. The average reaction times for Squads A and 

 B for other dates than October 28 and November 4, with the excep- 

 tion of the fragmentary data for November 11 (Squad A), always 

 show smaller values than on the original first date. Such a practice 

 effect is normal for untrained subjects in this measurement. It was 

 found by Dodge and Benedict in the eye reaction data in their alcohol 

 investigation.^ It is clearly evident in an unpublished series of eye 

 reactions secured with trained subjects in this Laboratory; it also shows 

 definitely in this low-diet research. 



^Very few data secured, but all are averaged in. 



^Action of shutter defective. 



For the individual men of Squad A, the average reaction times for 

 the whole series, from October 28 to January 27, range from 186 o- 

 {Gul) to 249 <T {Bro). Spe shows an average, 266 a, which is still 

 higher. He did not, however, have so much opportunity for practice. 

 All his reaction records show abnormally long times. The average 

 variability for the individual subjects ranges from 18 to 29 per cent. 

 The average reaction time for the whole experiment for the ten men 



iDodge and Benedict, Carnegie Inst. Wash. Pub. No. 232, 1915, p. 89. 



