The most common medium encountered in school learning is the book. As a medium, books can be characterized by the symbol systems they can employ: text and pictures. The following sections of the review will examine the cognitive processes used in processing text and text along with pictures. They will discuss how a distinctive characteristic of this technology--its stability--influences the processing of these symbol systems to construct knowledge representations and how these, in turn, are influenced by individual differences of learners, primarily differences in their prior domain-knowledge. The summary will describe how these processes and structures can be supported by by the author when designing a book.
The reading processes and the stability of the printed page. The primary symbol system used in books consists of orthographic symbols which, in Western culture, are words composed of phonemic graphemes, horizontally arrayed from left to right. That this arrangement is stable distinguishes text in books from other technologies that use the same symbol system, for example the marquee on Times Square. This stability also has important implications for how learners process information from books. Specifically, the stability of text aids in constructing a meaning of the text.
Learning with text involves the construction of two interconnected mental representations: a textbase and a situation model (Kintsch, 1988, 1989). The textbase is a mental representation derived directly from the text, both at the level of micro- and macrostructure; it is a propositional representation of the meaning of the text. While progressing through the text, the reader assembles the propositions and integrates them with ones previously constructed. As memory limits are reached, the most recent and most frequently encountered propositions are retained in short-term memory and held together by repetition or the embedding of arguments (Kintsch and van Dijk, 1978). The reader generalizes from these local propositions to form macropropositions, or summary-like statements that represent the gist of the text. Integrating the information from the text in this way increases the likelihood that it will survive in short-term memory and be fixed in long-term memory.