The degree to which printed text and graphics complement each other to facilitate reading comprehension was studied with the following four research tools: a system for analyzing text and graphics to reveal aspects of their form and content; procedures to permit analysis of both verbal and nonverbal recall measures of comprehension, allowing comparisons to be made with the original passage; eye track programs written to display text and graphics, collect data on readers' eye movements, and analyze the collected data; and a computer data analysis system. Research results indicated that certain specific types of information appeared to be better understood when presented in a particular form of text, graphics, or combinations of the two. The following specific results emerged: spatial or locative information is more completely and accurately understood when presented graphically than in text when the semantic content of each form is equivalent; information must be written and read in linear sequence; locative information presented in text form leads to comprehension difficulties; and sequential information is more effectively communicated in text than in illustrations. (Illustrations are included.) (DF)