The studies above show the range of ways that readers take advantage of the stable structure of text to aid comprehension. In the Bazerman (1985) study, strategic readers with considerable domain knowledge would sometimes progress through the text at a rapid rate, using a single word to skip a vast amount of information. Other times, they would slow considerably, moving back and forth within a text and across texts, to add to their understanding of the field. In other studies (Bayle, 1942; Shebilske and Reid, 1979), readers encountering difficulties with unfamiliar words, syntactic structures, or ideas used the stability of the printed page to slow their rate and regress over passages. None of these processing strategies are available with the transient, linguistic information presented in audio tape or lectures.
Multiple symbol systems: Learning with text and pictures. Orthographic symbols are, of course, not the only ones available to books. Pictures and diagrams are used in books from primers to college textbooks to technical manuals. But, how do readers use pictures? What is the cognitive effect of pictures in combination with text? And, how does the stability of these symbols, as presented in books, influence this process compared to another medium, say television, which presents linguistic and pictorial symbols in a transient way? This last, comparative issue will be directly addressed in the subsequent section on learning with television. The following section examines the cognitive effects of pictures and text.