PSYCHOLOGICAL MEASUREMENTS. 597 



the amplitude was still smaller on the last two low-diet dates, January 

 19 and 27. The refractory period (S) increases after the one normal 

 date, September 29, with Squad A. It is unusually long on December 

 8. Otherwise it is fairly uniform throughout the low diet sessions, and 

 is usually about 0.25 second. In the case of the four men of Squad B 

 with whom data could be secured there seems no significant change 

 until the very last date, January 27. This was on low diet, but it must 

 be noted to the contrary that the previous date, January 19, which was 

 also during the low-diet period, shows the shortest refractory interval 

 found with these men, but this average was for only two subjects, Sne 

 and Tho. 



The footnotes in tables 165 and 166 indicate a large number of cases 

 in which the tendency to summation of stimuli was present, i. e., the 

 production of one reflex for the two blows. This phenomenon of sum- 

 mation was found in only two cases with the normal series of 1917; 

 it was not found with any of the 26 men of Squads A and B in the first 

 measurement of the patellar reflex, and appeared only once (with Van, 

 November 3, table 166) during normal dietetic conditions. With 

 the reduced diet it was rather frequent (see Har, January 13 and 27, 

 Sne, January 27, for Squad B, and many other illustrations with Squad 

 A). When the sunmiation of the two stimuU produced but one reflex 

 it is of course impossible to give a figure for the refractory period. 

 That stimuli of 100-gram hanruners falling through 90°, which are 

 normally rather intense stimuli for the patellar reflex, should become 

 to the reflex as subliminal stimuli and only be effective when two 

 of them succeed each other by a short interval demonstrates the fact 

 that conditions exist in which the reflex irritability has become defi- 

 nitely less than normal. Whether this is primarily due to the re- 

 duced diet can not be absolutely proved from these data. The change 

 may be in part from adaptation to the form of stimuli. 



The evidence for the effect of the reduced diet upon the patellar 

 reflex as a neuro-muscular measurement is not uncomplicated. It is 

 our opinion, however, that there was a tendency for the reflex to be 

 less irritable when the subjects were on the reduced diet. 



(9) REACTION TIME FOR TURNING THE EYE TO A NEW POINT OF REGARD. 



The time required for the eye to change the direction of the line of 

 regard to an object appearing suddenly somewhere in the field of vision 

 usually ranges from 150 to 250 a, depending somewhat upon the amount 

 of practice that the subject has had in the test. This measurement 

 was used in the normal series of 1917 ; the apparatus and procedure were 

 identical with that employed in the low-diet research. From 10 to 

 35 reactions were obtained on each subject. A larger number than 

 10 was taken on every subject, but occasionally, for one cause or 

 another, some of the records would not be legible. Records from the 



