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Cognitive Effects of a Structural Overview in a Hypertext

Disorientation and navigation inefficiency are the consequences of the fragmented and incoherent structure of most hypertexts. To avoid these negative effects, researchers recommend—among other things—an interface with a structural overview of the relations between sections. Some authors have found that with such an overview, information is looked up faster and remembered better. This study examined whether a structural overview also leads to a deeper understanding. Forty students read a hypertext about the effects of ultraviolet radiation in one of two presentation conditions (structural overview and list). In the list condition, the same topics were mentioned as in the overview condition, but just in the format of a list. After reading, they answered textbase questions which measured their recognition and also inference questions supposed to measure their situation model constructed from the information read. The last type of questions indicated the readers’ understanding of the text. On textbase questions, subjects with low as well as high prior knowledge scored equally well in both conditions. In contrast to our expectation, the overview did not improve the recognition of main points. However, on situation model questions low prior knowledge subjects scored significantly lower in the overview condition than in the list condition. These results supported our hypothesis that a structural overview may hinder the understanding of less knowledgeable readers, because it draws their attention to the textual macrostructure at the expense of attention to the microstructure of the text.