io8 REPORT OF THE PSYCHOLOGY COMMITTEE 



are Intensely human documents. The first was a relatively 

 simple problem of analysis of reactions, adaptation of ap- 

 proved laboratory practice, and construction of a suitable 

 recording device. Four days after the receipt of the Inquiry 

 I outlined the Instrument that we used later, and I guaranteed 

 its success. The second was a problem of salesmanship. 

 Every gunnery officer who saw the instrument work was en- 

 thusiastic from the start, but It was months later before the 

 official wall of suspicion and red tape was passed. 



"On June ii, I reported the construction and successful 

 trial of an Instrument to test gun pointers. It gave a series 

 of graphic records of the fundamental processes involved In 

 training a gun on a moving target, under as nearly service 

 conditions as possible. Simple Inspection of these graphic 

 records, without elaborate computation, showed (i) the la- 

 tency of beginning the training of the gun to a movement of 

 the target; (2) the accuracy with which the actual movement 

 of the target was followed; (3) the latent time of reacting to 

 a change in the apparent motion of the target; (4) the effect 

 on the aim of pressing the firing key; (5) the accuracy of the 

 aim at the moment of discharge. 



"This instrument was set up and tested on expert marks- 

 men and Inexperienced recruits of the U. S. S. Georgia and 

 the U. S. S. Pennsylvania. The records show marked indi- 

 vidual dlfi"erences. The best gun-pointers gave the best rec- 

 ords; the untrained recruits the poorest. But among the 

 partially trained, some consistently followed the moving tar- 

 get with short reaction time and considerable satlsfactori- 

 ness; some showed promising Improvement within the five 

 trials permitted. 



"The instrument consists of an aluminum recording drum 

 mounted on a horizontal axis. This is turned at an even rate 

 through an arc of approximately ninety degrees by a weighted 

 piston falling in a cylinder of oil with a predetermined by-pass. 

 The weighted piston as it falls also moves the target in a horizontal 

 plane. Thus the target starts when the drum starts and stops 

 when the drum stops. A long recording lever (one meter) writes on 

 the drum with a lead pencil. This lever is moved by the person to 



