| Delivering text on electronic displays offers significant advantages to the user in terms of information access from a single device. It is important to make the display readable with the same level of comprehension and comfort as paper. The purpose of this research was to investigate various parameters that affect reading performance at increasing levels of cognition: legibility, visual search, and reading tasks.;A series of studies were conducted to identify and analyze the major parameters affecting legibility, which is defined as the recognition of letters and words. Another study investigated the relationship between legibility and reading performance of text based tasks: letter counting, word search, and reading speed. Following each task, subjects rated their discomfort: eyestrain, blurred vision, dry eyes, headache, and neck or backache, on a questionnaire.;The major parameters identified were letter case, pixel density, font type, and stroke width. Significant interactions were observed between display type and font smoothing. Legibility of upper case and lower case letters were not significantly different when letters were matched for size. Letters were more legible, by at least 10%, than words. Legibility increased with increase in pixel density up to 9 pixels (10-pt font) indicating that 10-pt characters contain sufficient detail for their identification. Sans serif fonts were more legible than the serif fonts, with Verdana being the most legible font tested. The use of bold letters enhanced legibility, whereas italic letters were less legible. The combination of Verdana and CIearType offered the best legibility among conditions tested.;For words, increase in character spacing improved word legibility considerably to the extent that word legibility matched letter legibility. This indicates that the reduced legibility observed at default character spacing is due to the crowding of the constituent letters. The implications of the results with respect to word perception are discussed. Reading speed, however, is significantly faster under default spacing than with altered character spacing.;Legibility was significantly related to readability. The results suggest testing of both letter and word legibility when investigating this relationship.;No difference in legibility or reading speed was observed between computer displays and paper under optimized display and text parameters settings. |
