The influence on learning of visuals accompanying self-paced text materials was investigated for students of varied reading comprehension ability levels. The use of varied degrees of realism and media presentation formats in facilitating learning on specific tasks was examined in order to clarify previous research, and to provide specific presentational guidelines for instructional designers considering a self-paced format. Programmed booklets with varied numbers of periodic review questions and answers and an additional audiotape were used to represent three levels of media presentation. Four levels of visual realism were studied: (1) no visuals; (2) line drawings; (3) shaded, detailed drawings; and (4) realistic pictures. Three levels of reading comprehension were identified for the 332 subjects. Visualization did not automatically result in improved achievement on different educational tasks for students of different reading comprehension abilities. The study demonstrated that individuals achieve at a different level of performance depending on the method of instructional presentation, the type of visuals accompanying printed instruction, and the level of reading comprehension. Further studies are necessary to provide the basis for detailed guidelines for developing self-paced visualized instruction. (LMM)