Systematic thinking fostered by illustrations in scientific text.

In 2 experiments, students who lacked prior knowledge about car mechanics read a passage about vehicle braking systems that either contained labeled illustrations of the systems, illustrations without labels, labels without illustrations, or no labeled illustrations. Students who received passages that contained labeled illustrations of braking systems recalled more explanative than nonexplanative information as compared to control groups, and performed better on problem solving transfer but not on verbatim recognition as compared to control groups. Results support a model of meaningful learning in which illustrations can help readers to focus their attention on explanative information in text and to reorganize the information into useful mental models. What can be done to improve the understandability of expository text? In particular, how can we design text so that readers will be able to use the information creatively to solve problems? To answer these questions, my colleagues and I have been engaged in a series of studies investigating the effects of advanced organizers (Mayer, 1975a, 1976, 1978, 1979, 1980, 1983; Mayer Mayer, Dyck, Sagerman & Mayer, 1987). This work has been based on the idea that different instructional manipulations may have effects on different aspects of cognitive processing in different learners. In particular, assimilation theory—the idea that learning involves integrating new information with existing knowledge—suggests three primary functions of cognitive processes: to guide selective attention towards certain information in the text, to foster the building of internal connections among ideas from the text, and to foster building external connections between ideas in the text and the learner's existing knowledge (Mayer, 1982, 1984, 1985, 1987). The present study opens a new line of attack by investigating the role of illustrations as potential vehicles for helping students understand expository text.