PSYCHOLOGICAL PROGRAM AND TECHNIQUE. 139 
A serious effort was made to secure sufficient data for every measure- 
ment with each subject to obtain a fair sample of the subject's per- 
formance. Usually not more than 10 to 12 minutes was required for 
any one measurement, while certain of the measurements required a 
period of only 5 minutes or even less. Under normal circumstances 
this is not sufficient to cause ennui or fatigue. 
The large variety of measurements made possible the employment 
of several men at the same time. Not infrequently a man may have 
some physical limitation which makes one or more of the measure- 
ments difficult or unpleasant to him. For example, he may have 
poor eyes, the knee-jerk may be absent, or he may believe that his 
memory is very poor. Such circumstances favor short intensive 
tests and several of them. 
PSYCHOLOGICAL MEASUREMENTS USED. 
The measurements which were chosen for this investigation may be 
catalogued under two heads: 
First, those given to the men as a group, that is, when all the men 
served as subjects at the same time, at the beginning of each evening 
session. These, listed more or less in their order of complexity, were : 
(1) Accuracy in tracing between irregular parallel lines. 
(2) Discrimination for the pitch of tones, 
(3) Discrimination for specified number groups on a printed page. 
(4) Addition of one-place numbers for a period of 10 minutes. 
(5) Memory span for 4-letter English words. 
Second, measurements given to the men individually; that is, when 
one man was tested at a time. These, numbered serially from the 
measurements previously given and listed in approximate order of 
increasing complexity, were: 
(6) Strength of grip (evening and morning). 
(7) Changes in pulse rate occasioned by short periods of exertion 
(morning). 
(8) Latency, amplitude, and refractory period of the patellar reflex. 
(9) Reaction time for turning the eye to a new point of regard (morn- 
ing). 
(10) Reaction time for speaking 4-letter words. 
(11) Continuous discrimination and reaction in finding serial numbers. 
(12) Sensory threshold for visual efficiency (acuity). 
(13) Sensory threshold for electric shock. 
(14) Speed of the eye movements (morning). 
(15) Speed of the finger movements (evening and morning). 
(16) Efficiency in traversing a right-angle maze. 
(17) Efficiency in performing certain clerical tasks. 
MEASUREMENTS BY THE GROUP METHOD. 
The group method was useful in this research, not only because it 
made possible a material saving in the time of the subjects, but it 
