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EMPLOYMENT PSYCHOLOGY 
practice. This practice should be written up in the most 
detailed and accurate form, and illustrated with examples 
so far as possible, so that other examiners, giving the same 
test and using the same directions, may likewise be giving 
the same demonstration and thereby obtaining the same 
standard results. As a supplement to this step, it is 
always advisable to give the subject a short preliminary 
trial in the test which he is about to take. Only in this 
way can the examiner be sure that his directions have 
been fully comprehended. To the unsophisticated mind, 
it may seem sufficient if the examiner, after having given 
the directions as clearly as possible, asks the subject: 
“Now do you understand?” and, upon receiving the 
answer “Yes,” proceeds with the test. However, no 
matter how intelligent the subject may appear, it is never 
safe for the psychologist to assume that his directions are 
grasped until he has had an actual preliminary demon 
stration on the part of the subject showing that they are. 
Many subjects only think that they understand, when, as 
a matter of fact, they do not; or they understand the 
wrong thing. Therefore, it is always advisable to give a 
very short, but characteristic sample of the test, in order 
to insure perfect comprehension on the part of the person 
being examined. This sample should always be of the 
same length and kind, to insure every subject the same 
degree of instruction and practice. 
Sometimes it is impossible to make the directions for a 
test clear enough. In that case, the difficulty probably 
lies with the test itself. This was the case in the Bogardus 
fatigue test described in Chapter X. The number of 
reactions made possible by this test were so numerous and 
variable, that it was also impossible to score the results. 
In such a case, it is necessary either to give up the test of