The influence of technical illustrations on students' comprehension in geography.

IN FIVE experiments we examined the use of illustrations in the comprehension of technical material by Australian high school students of good to very good reading ability. In Experiment 1, the same basic geographical text was read by three groups of 25 students each; additional, related content was presented (a) as an illustration, (b) as text, or (c) as both text and illustration. The presence of related content in an illustration did not improve comprehension of the basic content; however, the group that received the additional content as both text and illustration (Group 3) outperformed the other two groups on that content. These data suggest that illustrations may present information in their own right rather than serving merely as adjuncts to aid comprehension of text. These results were examined further in four more experiments with various designs and a total of 204 students. In Experiments 2, 4, and 5, content presented in the form of both text and illustration resulted in higher comprehension than simple repetition of either the text or the illustration. In Experiments 2, 3, 4, and 5, content presented in an illustration only was comprehended better than the same content presented in text only. These results suggest that technical content that lends itself to presentation as an illustration will be comprehended better as an illustration than as text, and will be comprehended best of all if presented in both forms. These results have important implications for the design of textbooks and other presentations of technical material. Authors should take at least as much care in the drawing of illustrations as they take in the writing of the text.