OF THE NATIONAL RESEARCH COUNCIL I3i 



But in spite of many difficulties the psychological program 

 was initiated and carried through a month of intensive work. 



"Throughout the investigation the subject was myself. 

 A number of circumstances made this somewhat questionable 

 procedure necessary. In the first place, I needed first hand 

 information of the efi'ects of the mask. Moreover, in my own 

 case there was available abundant data on the normal varia- 

 bility of my responses. So I could evaluate a few experiments 

 on myself better than on an unknown subject. Finally, the 

 lack of available assistance made it impossible to begin in 

 any other way. 



"The observations were of two sorts: (i) A serial record 

 of personal impressions. While this was quite inexact and 

 liable to distortion by personal bias, it was the only criterion 

 in matters of relative comfort and discomfort. Moreover, 

 for an observer who is trained to avoid the commoner illusions 

 of self-observation, the method will give considerable insight 

 into the presumptive facts over a wide field. (2) In addition 

 to these personal impressions, quantitative measurements 

 were made of a group of selected processes that seemed likely 

 to be significant on psycho-physiological or military grounds. 



"When the investigation began there was no available 

 tradition of the probable effects of gas-mask tenancy. Based 

 on the previous studies of fatigue and of the psychological 

 effects of alcohol, I selected the following processes for meas- 

 urement: 



1. The duration of the pulse and respiration cycles during rest, 

 measured work, and the recovery after work. Pulse is the best- 

 known indicator of general physiological condition. Our pulse rec- 

 ords were electrocardiograms. 



2. Visual acuity as measured by the grating test object. The 

 relation of visual acuity to military efficiency needs no comment. 



3. Simple reaction of the hand to a visual signal. This was 

 undoubtedly too simple a form of reaction, but no suitable military 

 task seemed available on short notice. 



4. Eye reactions were photographed by the usual technique. 

 They are involved in every adjustment of a soldier to events that 

 he can see. It is a more complicated form of reaction than the 

 simple finger reaction, is more universally practiced, and probably 

 more significant in its changes. 



