74 



PRINTED MATERIALS, MAPS, CHARTS 



Perceptual Patterns 



Many of the creative skills of cartography 

 have been apphed to the task of giving valid 

 perceptual representation to such features as 

 coastal regions, mountains, slopes, and 

 under-water contours by such devices as 

 engraving, hachuring, sanding, tinting, and 

 shading. In recent years the demands for 

 faster production, economy, and more usable 

 quantification of data have tended to shift 

 the emphasis away from such pictorial char- 

 acteristics. At the same time, aviation has 

 tended to shift it back by demanding flight 

 charts with easily recognizable landmarks. 

 It is sometimes necessary, as, for example, 

 in atlas maps and some aeronautical charts, 

 to present so much information that it is 

 difficult to select the desired items visually. 

 An attempt to formulate in general terms 

 the principles of perception relevant to these 

 problems, drawing on both the experience of 

 cartographers and the academic literature, 

 would be profitable. 



Unfavorable Conditions, Work Output, and 

 Fatigue 



In the routine of navigation, work with 

 charts is hkely to be alternated with other 

 visual tasks over considerable periods of 

 time. For reading under non-optimal con- 

 ditions such as red lighting and vibration, 

 the legibility data now available may not 

 offer a vahd index of the level of reader per- 

 formance which can be expected in terms of 

 speed, accuracy, and resistance to fatigue. 

 It is therefore important that the literature 

 reviewed above on visual performance under 

 good conditions be supplemented by more 

 systematic studies of those less favorable 

 conditions, and that the problem of visual 

 fatigue be investigated further. 



Research Suggestions 



A few of the broader areas for possible 

 research suggested by this survey are re- 

 capitulated in the following list. 



1. Since general theory serves the ends of 



economy in the long run, basic research in 

 this field should be encouraged. 



2. A clarification of the general problem 

 of visual fatigue and energy cost on either the 

 theoretical or the empirical level is to be 

 desired. (Bitterman, Ryan, and Cottrell (7) 

 are currently investigating the possibilities 

 of the muscle-tension criterion in this con- 

 nection.) 



3. Applying the principles of visual acuity 

 and discrimination to the designing of a 

 type face of maximum perceptibility under 

 near-threshold conditions might pay returns. 



4. More extensive studies of the use of 

 printed materials and charts under adverse 

 conditions, when performance is measured 

 as a function of several variables, would fill 

 a noticeable gap in present knowledge. 



5. Recent developments have created a 

 need for more information about the relative 

 effectiveness of different color arrangements 

 in maps and charts, especially in relation to 

 different light sources. 



6. As a somewhat more speculative sug- 

 gestion, an exploration of the principles of 

 perception in relation to tables, graphs, 

 maps, and charts might prove of interest. 



Summary 



Representative research on the factors of 

 typography, illumination, and fatigue in nor- 

 mal reading has been reviewed, especially 

 with reference to the more controversial 

 methodological problems. Work on percep- 

 tion of type at a distance and on the legibility 

 of numerals has been examined in relation 

 to the factors in normal reading and to the 

 characteristics of the visual receptors. 

 Studies of tables and graphs have been sum- 

 marized, problems of the use of maps and 

 charts have been surveyed, and possible 

 areas of further research in relation to 

 printed materials, maps and charts have 

 been suggested. 



References 



1. Armstrong, R. C. Aeronautical charts pre- 

 pared for use in darjlight, under white, ultra- 

 violet, red and amber lights. USAF Air 



