Accession Number : AD0420010

Title :   STUDIES OF DISPLAY SYMBOL LEGIBILITY. PART II. THE EFFECTS OF THE RATIO OF WIDTHS OF INACTIVE TO ACTIVE ELEMENTS WITHIN A TV SCAN LINE AND THE SCAN PATTERN USED IN SYMBOL CONSTRUCTION,

Corporate Author : MITRE CORP BEDFORD MASS

Personal Author(s) : Botha,B. ; Shurtleff,D.

Report Date : SEP 1963

Pagination or Media Count : 25

Abstract : The purpose of the present study was to investigate the effects on legibility of several factors characteristic of linear scan methods (TV raster) of symbol construction and display. These factors were: (1) The ratio of the widths of inactive to active elements within a TV scan line, (2) the scan pattern (the path of the scan element over the symbol) used in symbol construction. Another purpose of the study was to determine whether the method of symbol illumination (reflected light vs. transilluminated light) had an effect on legibility. Two groups of subjects viewed tachistoscopically transilluminated capital letters at a .03 sec. exposure for each of three different ratios of the widths of inactive to active elements within a TV scan line. Each group viewed letters constructed by a different scan pattern. The results showed that both accuracy and speed of response in letter identifications decreased as the ratio of the widths of inactive to active elements increased. The scan pattern used in the construction of letters had a progressively greater effect on response accuracy as the ratio of the widths of inactive to active elements within a TV scan line was increased. The method of symbol illumination had no effect on either response accuracy or speed. (Author)

Descriptors :   (*TELEVISION DISPLAY SYSTEMS, EFFECTIVENESS), LINEAR SYSTEMS, SCANNING, ILLUMINATION, PSYCHOLOGICAL TESTS, ANALYSIS OF VARIANCE

Distribution Statement : APPROVED FOR PUBLIC RELEASE