172 



PANEL DESIGN 



trols and displays relevant to the layout 

 problems of the moment may be manipu- 

 lated for experimental test. 



The final check-out of equipment will have 

 to be made on experimental models of the 

 equipment. These models should be flex- 

 ible enough to permit the experimental in- 

 troduction of alternative designs and ar- 

 rangements of controls and displays without 



ORIGINAL PROCEDURE 



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IMPROVED PROCEDURE 



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Fig. 10. Modification of the procedure of cock- 

 pit check-off to reduce waste motion. (From 

 Channell, 7) 



detracting from verisimilitude. At this 

 stage, however, the process of evaluating 

 performance becomes complex and requires 

 fairly refined techniques such as those used 

 in industrial time and motion studies. In 

 the first place, we are deaUng with complex 

 behavior and have to resort to technical 

 devices for recording it. Two major tech- 

 niques that have been used in industry seem 

 appropriate here: (1) micromotion analysis 

 in which motion pictures of operators at work 



are used to indicate the motion paths that 

 are followed in the use of controls, the 

 amount of time spent in the operation of 

 each control, the speed of reactions, and the 

 relative use of parts of the body, and (2) eye 

 movement records which indicate the fre- 

 quency and duration of fixations of displays 

 and the patterns of eye movements from one 

 display to another. In addition, wherever 

 possible, it is of value to have an overall 

 measure of the speed and accuracy of per- 

 formance such as the rate at which informa- 

 tion can be put through equipment used in 

 communication centers, the accuracy or 

 range and bearing readings in radar opera- 

 tions, the length of time a man can work 

 efficiently at a plotting board under stand- 

 ardized conditions. Finally, by appropriate 

 questionnaire techniques the opinion of typi- 

 cal operators should be obtained on such 

 questions as the comfort of the seating ar- 

 rangement, the importance of controls and 

 displays, and their preference for alternative 

 arrangements of the panel. In all of these 

 measures of performance and opinion, it is 

 important to use a reasonably large sample 

 of subjects, representative of the operators 

 who are Ukely to use the equipment in re- 

 spect to age, education, intelhgence, physical 

 size, and aptitude. 



Equipment in Current Use 



In actual practice, much of this evaluation 

 work has to be done on equipment in current 

 use where there is little opportunity to ma- 

 nipulate panel layouts or introduce changes in 

 design. The problem at this stage is pri- 

 marily one of determining whether or not 

 the panel design and arrangement embodies 

 the best of present day knowledge and prin- 

 ciples of the layout of controls and displays. 

 For different types of equipment different 

 problems will have to be faced, of course. 

 Some control and display panels are difficult 

 to use because they are so complex; others 

 are relatively simple but require a person to 

 operate a small number of controls with great 

 precision or to work for long hours. In any 



