LEGIBILITY OF TYPE AS A FUNCTION OF STROKE LETTER WIDTH, AND LETTER SPACING UNDER LOW ILLUMINATION

摘要

The legibility of small type as a function of letter width, stroke width, and letter spacing was measured for capitals and lower case under low and high illumination. Experimental type approximating a 6-point Gothic style was designed for the purpose. Speed and accuracy scores were obtained on a letter crosscut task in part of the experimentation, and on an oral reading task in the remainder. Effects of the typographi¬cal variables were more marked under low than under high illumination. "Regular" letter width was considerably better than "condensed". For most of the varieties of type studies, stroke width was found to have an optimum in the neighborhood of 2556 of mean letter width, and spacing an optimum at about 50/C of mean letter width. Capitals could be read more readily than lower case when occupying the same printing area.nThe results of this report are of value to the U. S. Air Force in that the basic principles can be applied to the design of aeronautical charts and check lists.