WHAT PSYCHOLOGY CONTRIBUTED 387 



Let me illustrate this kind of war work by a single concrete 

 instance in which the details are not military secrets. The first 

 problem that was referred to the sub-committee on vision was 

 the question whether we had any way of selecting those naval 

 recruits who could be trained most quickly as gun-pointers for 

 the armed merchant ships. 



The first step was to learn exactly what a gun-pointer had to 

 do. The next was to reduce the more or less complicated pro- 

 cesses of gun-pointing to their simplest neuro-muscular terms. 

 It was a definite problem for analysis ; and, because of the perfect 

 systematization and high specialization of naval tasks it was rela- 

 tively simple. The third step was to adapt approved scientific 

 technics to the study of this particular complex of neuro-muscular 

 processes. For this purpose an instrument was devised that would 

 show all the following facts on a single record line: i, the time 

 that it took a sailor to start his gun-pointing reaction after the 

 target at which he was aiming started to move; 2, the accuracy 

 with which he was able to " keep on " the moving target ; 3, the 

 time that it took him to respond to a change in the direction of 

 motion of the target ; 4, the ability to press the firing key when he 

 was on; 5, the effect of firing on his pointing. (See frontispiece.) 



All these data were so simplified that they could be accurately 

 estimated from simple measurements of a single line without 

 elaborate computations. A succession of records indicated the 

 probable quickness with which the sailor would learn the new co- 

 ordinations. The final step was to test the probable military value 

 of our instrument and its records by performances of expert and 

 inexpert gun-pointers. 



The first trials proved the usefulness of the device. It clearly 

 differentiated between the qualified gun-pointers, the partially 

 trained, and the untrained. It picked a number of promising 

 novices and indicated the faults of some who were slow to improve. 

 Predictions based on the records were uniformly corroborated by 

 subsequent experience. Somewhat later it was possible to con- 

 struct a robust training instrument along similar lines that was 

 rather enthusiastically reported on by various naval officers, and 

 was widely reproduced by the navy for use in the Naval Training 

 Stations. 



At a time when every available gun was needed for service 



