Ii8 REPORT OF THE PSYCHOLOGY COMMITTEE 



7. Candidates who reach a grade of 75 per cent, in this elimina- 

 tion test are given an individual examination in their ability to 

 discriminate phase difference, with a stethoscope attached to a 

 rubber tube. This individual test also serves the following pur- 

 poses: (a) To check other sources of information covering the can- 

 didate's personal qualifications, (b) To estimate the quickness 

 and certainty of his reactions. 



8. The final process in the selection of candidates for the Lis- 

 teners' School was conducted by myself. In this examination It is 

 assumed that all candidates have the minimum qualifications de- 

 tailed above. No regular effort is made to check these qualifica- 

 tions except in the matter of schooling. Before examining a candi- 

 date a brief typewritten statement of instructions Is given to him. 

 Failure to understand or to follow these Instructions leads to a more 

 careful review of the candidate's general intelligence. 



9. The purposes of the final examination are: 



(a) To serve as a check on the preliminary elimination In the 



several Naval Districts and to standardize the results. 

 That Is: It sometimes happens that in filling its required 

 quota one District Is compelled to include some men of a 

 relatively low grade. By comparison of all the candidates 

 at one place it is possible to apply a common standard 

 Irrespective of the Naval Station from which they came. 



(b) To estimate a number of factors that could not easily be 



tested without special training and apparatus. 



10. The Instrument used for making the final examination Is a 

 simplified compensator designed for the purpose and is constructed 

 as follows: 



On a suitable standard two concentric wooden wheels are 

 mounted. One wheel facing the examinee measures thirty cm. In 

 diameter. This is his compensating wheel. The compensating 

 wheel Is operated by the examinee as though It were a real compen- 

 sator. The other wheel just behind the standard and hidden from 

 the view of the examinee measures 26 cm. The position of this 

 wheel determines the difference In wave phase. It carries on Its 

 periphery the middle third of a rubber tube which is two meters 

 long. The ends of the tube are carried through the hollow axis 

 of the wheels to a stethoscope. The exact middle of the tube Is 

 plainly marked on the operator's side, and the tube Is cemented 

 firmly in place on the wheel. The concentric wheels can be turned 

 independently to prevent secondary identification marks. Slight 



