PERCEPTION OF PRINT AT A DISTANCE 



67 



prehensive studies are to be preferred over 

 studies of variables in isolation. 



Second, the energy cost of reading is an 

 obscure factor, the consequences of which 

 have not been demonstrated by the evidence 

 to date. The matter can hardly be left with 

 the implication that therefore the cost must 

 be neghgible, because the problem may be 

 accentuated for visual work under difficult 

 conditions. JMore dependable measures in 

 this area are needed. 



Third, the emphasis in these studies has 

 been on optimal conditions. Unfavorable 

 reading situations hkely to be encountered 

 in practice have received much less syste- 

 matic attention. 



Inferior Materials 



Examples of unfavorable reading condi- 

 tions are the low quality paper used in pulp 

 magazines and paper bound books, and the 

 low intensity of illumination needed at some 

 posts to protect the reader's dark adapta- 

 tion. Scattered studies of various materials 

 of inferior quality, such as newspaper print, 

 typed carbons and originals, stencil dupli- 

 cated copy, and comic book lettering, have 

 sho^vn a need for higher illumination levels 

 (Tinker, 51). With such materials there is 

 also an impairment of reading speed and 

 large variability in "visibility" meter meas- 

 ures (Leckiesh and Moss, 30, Chap. IX). 

 Thus, results of fatigue studies which employ 

 good quality print cannot safely be extra- 

 polated to such materials. 



Microfilm 



Microfilm presents a marginal reading 

 situation which might at some future time 

 become the norm. iMcFarland, Holwa}^ and 

 Hurvich (31, pp. 76 ff.) found no significant 

 difference in blink rate between microfilm 

 and book reading, but their subjects pre- 

 ferred to read the book. When given a 

 choice of two illumination levels on the 

 microfilm surface, the subjects chose the 

 lower (31, p. 189). In the Carmichael and 

 Dearborn study (10) eye movement meas- 



ures differentiated between microfilm and 

 normal book reading for high school but not 

 for college students. Subjective reports of 

 boredom and fatigue were in general more 

 frequent for microfilm. This the authors 

 attributed to the more awkward sitting posi- 

 tion for microfilm reading. It appears from 

 these results that any departure from the 

 normal reading of good quality book type 

 introduces new factors requiring separate 

 evaluation. 



Perception of Print at a Distance 



The reading of placards and posters differs 

 from book reading in important respects. 

 There is relatively little content to aid per- 

 ception. Distance often puts the material 

 near the threshold of discrimination, and 

 because the material is usually brief, the 

 "work" component is reduced to a minimum. 

 This situation is approximated in the exper- 

 imental procedure of testing legibility by de- 

 termining the distances at ^^ hich words and 

 letters can be identified. Results by this 

 method agree with those in terms of reading 

 speed in the following respects : 



1. Relative legibility with different color 

 combinations is roughly proportional to their 

 brightness contrasts (Preston, Schwankl, and 

 Tinker, 35; Sumner, 42). 



2. Type of paper surface makes no differ- 

 ence (Roethlein, 38 ; Webster and Tinker, 56) . 



The two methods yield quite different 

 results when type form or style is the vari- 

 able: 



1 . Though lower case is read more rapidly, 

 capitals can be identified at greater distances 

 (Tinker, 49), possibly because capitals cover 

 larger areas. 



2. Different type faces have quite different 

 thresholds. Roethlein (38) presented letters 

 singly and in combinations in a large number 

 of type faces. She concluded that details of 

 design are the least important, and relative 

 boldness of the type faces one of the most 

 important, factors, and that combinations 

 of adjacent letters of similar outline, such as 

 d and b, impair discrimination. Webster and 



