The laboratory measurements used in the psychological phase of this research on the effects of short rations have been described in an earlier chapter. (See p. 137.) It will suffice here to note that careful instructions preceded each measurement. At the first two sessions with each squad the instructions were fairly detailed. Later it was only necessary to emphasize the chief points, each of which could be called to the subject's mind by a word or two from the one taking the measurement. In the group work the instructions were always detailed. It is a pleasure to record the serious attitude, the remarkable cooperation, and general fine spirit of the men who served as subjects in both Squads A and B. They readily consented to do whatever was asked of them. There was no tendency to beg to be excused, to shirk, or, on the other hand, to frustrate experimental plans. In the matter of willingness and attitude the men who served left little to be desired.

Attention has been called (p. 491) to the conditions which made it imperative to begin the reduction in diet almost immediately after the opening of the college year. These circumstances of course rendered it impossible to secure an adequate base-line in the psychological measurements with Squad A. The men came to the Laboratory only once (September 29) before the reduction in diet commenced, this beginning October 4. Of course one session, and particularly an initial session, is not adequate for a normal in most of these measurements. On the first evening the experimental program naturally progressed more slowly, since it was necessary to give complete instructions to all the subjects, none of whom were familiar with any of the tests. Moreover, there was a time limit beyond which it did not seem wise to extend the evening session, since the men were also to serve as subjects in the group respiration chamber during the night. It was thus impossible at first to give the full program of measurements, and hence with some tests there is no normal whatever for the men of Squad A. This condition is regrettable, but could not be avoided. Serious consideration was given to the possibility of taking measurements on Squad A after they had returned to normal and uncontrolled diet following the experiment. It will be evident to anyone who examines the data and comments which relate to the condition of Squad A during the first and second weeks following the conclusion of our investigation, that such post-diet measurements would have been unsatisfactory and could not have been considered as normal base lines. At that time the men grossly overate; many of them suffered from digestive troubles, and, in general, appeared to be indulging in what might be termed a "food spree." The period following such a reduction in diet as these subjects underwent should be investigated for its own sake and can not be rightfully assumed as a normal. Under peace-time circumstances the men composing Squad A would usually have remained in college for two or three months subsequent to the experiment, a period which supposedly would have allowed them to become adjusted to their natural dietetic habits. At the end of such a period they doubtless could have been obtained for one or two sessions of normal measurements. It is needless to explain the impracticability of such a plan in 1918. In fact, it was exceedingly difficult to hold the subjects together until the end of the diet experiment on February 3, and in some cases it was necessary to have men excused temporarily from the Government service. Very shortly after the end of the experiment, 6 of the men in Squad A had left college and were in various fields of Government work.

Squad B did not begin the reduced diet until January 8, and remained on the low diet about 3 weeks, or until January 28. Hence, a greater part of the measurements with this squad were under supposedly normal conditions. If it is ever permissible with squads of 10 men to take the normal psychological results for one group and assume them to be a normal measure for another group, then it is permissible here. The men composing Squad A and Squad B came from the larger homogeneous body at the International Y.M.C.A. College. The men were not selected for one squad or the other on a basis of scholarship; in fact, their scholastic records show that the groups rank about evenly in this regard. Furthermore the squads compared very well in age and physical ability, although, in general, upper classmen were taken for Squad A. Doubtless, as there was some group spirit, each squad considered itself superior to the other, but as subjects for laboratory experiments in psychological measurements there was no prominent difference between them. Squad A had somewhat the advantage on the side of laboratory practice, since, in the early fall, they came regularly every 2 weeks, while the sessions with Squad B were sometimes separated by 4 weeks and the latter squad had a total number of 8 laboratory sessions, while the former squad had 10. (See chronological record, p. 60).

With some of the measurements there are already at hand considerable normal data for comparison purposes. In the spring and early summer of 1917 a series of neuro-muscular and psychological observations were carried out at the Nutrition Laboratory with a group of 63 college men who were prospective aviators attending an aviation ground school. These subjects were mostly upper classmen or graduates from Harvard, Yale, and other leading universities. They were in many respects a picked group of men who had passed the requisite physical examination. They served one normal session of approximately 1 1/2 hours, which followed the evening meal as did the sessions of the reduced diet subjects. With the 63 college men of course the eating was uncontrolled. Much of the apparatus used for the low-diet research was likewise employed for the aviators. The laboratory-conditions were perfectly comparable, and the procedure with the measurements was nearly identical. These data will be referred to from time to time for purposes of comparison, and will be designated as "normal series of 1917".