72 



PRINTED MATERIALS, MAPS, CHARTS 



compiling the material to be shown from a 

 diversity of sources which have to be sepa- 

 rately evaluated, and that of generalizing 

 such features as contour lines and soundings 

 to the best advantage when the scale is being 

 reduced, require a high degree of professional 

 judgment. Artistic skill is often called into 

 play in the final arrangement of details to 

 effect a pleasing appearance and to reflect 

 correctly the relative importance of the vari- 

 ous features in relation to the needs of the 

 users. 



A further comphcation in map making 

 stems from the rapid changes in technology 

 of recent years. Changes have been necessi- 

 tated by demands for increased precision, 

 for faster corrections and revisions, and for 

 larger numbers of copies requiring long print- 

 ing runs. They have been made possible by 

 new techniques and materials such as photo- 

 aluminography and transparent plastic 

 sheets. These developments have some- 

 times modified the perceptual effects pro- 

 duced. Lettering, for example, was formerly 

 hand engraved, in styles which had been 

 designed for the purpose. The current trend 

 is to print lettering from type. As the 

 preparation of map plates sometimes in- 

 volves photographic reduction, a given type 

 may ultimately appear in a size for which it 

 was not originally designed. The photog- 

 raphy sometimes results also in a loss of 

 sharpness in internal corners. Legibihty 

 may suffer as a consequence. Another 

 change is the decreased use of the stippled 

 effect kno'HTi as sanding for showing gradu- 

 ations of depth in coastal waters, with in- 

 creased dependence on contour lines and 

 tinting. This change saves time in correc- 

 tions and revisions, but the new perceptual 

 effect is quite different from the old. 



In addition to technological changes, new 

 circumstances of use may create new prob- 

 lems. Aviation has brought a need for flight 

 charts with easily recognizable topography. 

 Arctic flight has forced a consideration of the 

 type of projections most suitable for polar 

 regions. Red lighting which is designed to 



protect dark adaptation changes the con- 

 trast effects produced by tinting, and the low 

 brightness increases the difficulty of discrimi- 

 nating fine print. Expansion of submarine 

 activity has increased the need for effective 

 portrayal of undersea conditions in three 

 dimensions. 



Complex and changing circumstances in- 

 crease the cartographer's difficulty in keep- 

 ing in rapport with operational needs. A 

 minor example can be cited. There is an 

 organized and efficient interchange of infor- 

 mation between the makers and the users of 

 nautical charts on harbor and coastal con- 

 ditions, but the coordination seems to be 

 less close on details of working arrangements. 

 Submarine officers have pointed out that 

 small table surfaces make it necessary to 

 fold the charts, which hides the marginal 

 scales and increases the difficulty of plotting. 

 Repeating the scales at intervals on grid 

 lines should solve the problem. 



Returning to the psychological aspects of 

 map and chart reading, we can ask what 

 inferences seem indicated by the work on 

 printed materials discussed above. One in- 

 ference is that, with maps as with print, 

 unpredictable interactions would necsesitate 

 caution in extending experimental conclu- 

 sions beyond their original context. With 

 this limitation in mind, we can expect that 

 the experimental approach would provide as 

 valuable information in the one area as in 

 the other. 



Turning to more specific problems, it 

 seems safe to consider that brightness con- 

 trast within the materials to be discriminated 

 is a general principle of importance for visual 

 work. This highlights the desirabihty of 

 more information about the reading of sym- 

 bols under low contrast as is often necessary 

 with maps and charts. 



A somewhat related proposition that ap- 

 pears generally valid is that the acuity and 

 discrimination mechanisms are of increased 

 importance as conditions approach thresh- 

 olds, e.g., in type size or brightness. This 

 directs attention to details of type form. 



