STUDIES OF HUMAN FACTOR IN PANEL DESIGN 



165 



the items in the system, in this case, the 

 controls and displays on the panel. Links 

 may be defined in terms of both the 

 frequency with which the use of one control 

 or display follows another in time and the 

 importance that may be attached to using 

 two items in succession. This information 

 may be obtained by surveying the opinion 

 of experienced operators, micromotion anal- 

 ysis, and eye movement recording. Once 

 it is obtained, some sense can be made of 

 the problem of functional grouping of con- 

 trols and displays by simple graphical solu- 

 tion. Each control and display may be de- 

 picted on a chart, and for each link it 

 has with another control or display in 

 actual operation, a Hne may be dra^n from 

 one item to the other. Then the controls 

 and displays can be arranged on the chart 

 so that they are closest to the other items 

 with which they have the most frequent and 

 important links. Finally these relative spa- 

 tial relations can be used as a guide for the 

 placement of items within the practical 

 working limits of the panel. Up to the 

 present, this technique has not been used 

 in panel layout problems. However, its suc- 

 cessful application in the arrangement of 

 communication centers recommends it for 

 further experimental evaluation in connec- 

 tion Avith panel layout problems (Fig. 8). 



Patterns of Movement 



The argument for functional grouping of 

 controls has been made even more strongly 

 than in the case of displays, for waste mo- 

 tion of the trunk and hmbs is considered 

 even more conducive to fatigue and impaired 

 performance than waste eye movement. 

 Within any functional group of controls, 

 however, there is still the problem of proper 

 placement of individual controls in the most 

 efficient pattern for operation. On the basis 

 of industrial studies certain types of move- 

 ment are recommended as the more easily 

 performed by humans: balhstic movements, 

 curved movements, continuous movements, 

 and use of the two hands simultaneously in 



JE 

 1234 



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2 FGL 



3 LMH4 



4 EL3 



B. GRAPHIC SOLUTION 



Fig. S. Analysis of functional links in a com- 

 plex man -machine situation, showing the original 

 design of a communications center (A), the graph- 

 ical solution of link values (B), and the improved 

 design (C). (After Chapanis et al., 9) 



