264 



VISUAL COMMUNICATION 



has the difficulty of being readily inter- 

 cepted, and of being entirely impossible un- 

 der conditions of radar silence. This 

 method essentially is a method of ''oppor- 

 tunity," useful only on certain relatively 

 unpredictable occasions. 



Communication by Instrument Display 



The last method of visual communication 

 to be considered may be termed communica- 

 tion by instrument display. This class in- 

 cludes all the various kinds of visual com- 

 munication employing the visual displays 

 typical of machine to man couples. 



At the present time, no use of these is 

 made in exterior communications, but in in- 

 terior communications a few scattered and 

 poorly designed equipments may be seen. 

 The engine-order telegraph and the torpedo- 

 gyro control panel are examples of such sys- 

 tems. Almost all machine to man couples, 

 however, are of this variety. Dial faces, 

 both clock-face and odometer; simple signal 

 lights, such as the glowing red jewels which 

 indicate closed circuits; the complicated 

 status patterns of illumination of the sub- 

 marine's "Christmas tree"; all of these com- 

 municate the activities and status of me- 

 chanical systems to a receiver by the use of 

 symbols. 



It is such systems, presenting a panel dis- 

 play of visual symbols, that most effectively 

 utilize the visual capacities of the human for 

 the purpose of communication. None of the 

 restrictions on exterior visual communication 

 that are set by the varying ranges and atmos- 

 pheric conditions are met here, since the 

 receiver is always within a restricted distance 

 of the panel, and since the interior illumina- 

 tion is close to constant. The visual prob- 

 lems encountered are those already under 

 investigation in studies of machine to man 

 communications, and the results of these 

 may be applied to the special problems of 

 man to man communication. 



The limitations which are of importance to 

 such systems stem from the need for training 

 of sending and receiving personnel. After a 

 careful study of the problems involved, it is 



probable that communication by the display 

 of visual symbols on panels may be effective 

 in improving present communication sys- 

 tems. 



Interior Communication by 

 Instrument Display 



The problem of communication systems is 

 rather different for the psychologist than it 

 is for the physicist. The problem of the for- 

 mer is that of investigating systematically 

 the various behavioral and sensory means 

 whereby one individual, the sender, may 

 control the behavior of another, the receiver, 

 through the use of symbols. The physicist 

 or engineer is faced with the complementary 

 problem of designing physical systems capa- 

 ble of transmitting the symbols initiated by 

 the sender to the receiver over some distance. 

 The proposals to be made are based on the 

 psychologists' findings, and may be expected 

 to pose special problems to the physicist and 

 electrical engineer. The writer, a psycholo- 

 gist and not an engineer, recognizes that 

 some of the procedures suggested may not 

 be capable of being effected by equipment 

 already designed. However, we shall pro- 

 ceed to make concrete suggestions, with con- 

 fidence that the electrical engineer can even- 

 tually solve the problems that are involved. 



Indispensable to the study and develop- 

 ment of instrument methods of visual com- 

 munications is a preliminary study of the 

 communication traffic carried by each of the 

 existing telephone and speaker circuits. A 

 complete classification, census, and content 

 analysis, of all these messages and of their 

 origins and intended destinations, should re- 

 veal clear-cut distinctions between neces- 

 sary® and unnecessary communications in 

 content and in direction of messages. 



^ Necessary messages are here defined as those 

 which must be immediately and accurately received 

 if efficient control of a vessel is to be maintained. 

 They are those in which misunderstanding or 

 delay in transit may have serious consequences 

 for the success of the vessel in its mission. 



