Cognitive overhead in hypertext learning reexamined: overcoming the myths.

In hypertext learning, comparative research is mostly dedicated to differences in text-hypertext information retrieval and processing and to optimization of nonlinear information retrieval. Most of these investigations are conducted within the context of applied research. The theoretical background of information acquisition from linear and nonlinear text forms has not received much attention here. This article contributes to change the concept of cognitive overhead using text comprehension models as well as Cognitive Load Theory. Similarities and differences in cognitive load during text and hypertext comprehension are discussed in this context. The article suggests a contemporary model of cognitive load and text comprehension and presents evidence from a review of the literature and an initial empirical study supporting the proposed model.

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The increased availability of electronically stored documents has led to a more frequent use of digital text resources in education. Especially in higher education, the ability of colleges or universities to create online-publications and e-learning opportunities provides a huge variety of materials across most disciplines.

Computer-based text formats differ in many characteristics from traditional print texts. The most common form beside camera-ready downloadable files (as many scientific papers or e-journals are presented) is the hypertext. Hypertext is also the basic format for World Wide Web (WWW or Web) documents using Hypertext Markup Language (HTML). The nonlinear information retrieval allows readers or learners to access different paragraphs (nodes) in an almost self-determined manner merely depending on a hypertext author's navigation paths established within a hypertext. It is an ongoing debate among learning scientists whether the nonlinearity of hypertexts promotes learning or whether it is unbeneficial for knowledge acquisition (Rouet & Levonen. 1996).

Researchers and teachers pursuing a constructivist view of learning favor hypertext as a learning medium. Much of the research and its application have followed the Cognitive Flexibility Theory (CFT: Jacobson. Maouri, Mishra, & Kolar, 1996: Jacobson & Spiro. 1995; Niederhauser, Reynolds, Salmen, & Skolmoski, 2000; Spiro & Jehng, 1990). CFT states that learners benefit from an information retrieval that is a "landscape-crisscrossing" rather than a linear knowledge acquisition process. Hypertexts in context of CFT are viewed as adequate media to go beyond certain information, to (re-)visit certain facts at different times and in a different context. Thus, learners should ideally develop complex schemata that enable them to use their knowledge in a flexible manner.

Common to all these approaches is the use of hypertext in an attempt to present information in its full complexity and to enhance transfer by providing learners with the opportunities of thematic crisscrossing. Recent research has shown that this rationale does not necessarily meet the expected results. Some findings suggest disadvantages of jumping between themes (Niederhauser et al., 2000); others found only slight advantages (Jacobson et al., 1996) or only found an effect when instructional support was used in addition to hypertext learning (Stark, Graf, Renkl, Gruber, & Mandl, 1995). While these authors have used hypertext as a learning environment itself, other authors integrated hypertext learning resources into broader computer-based learning environments (Scherly, Roux, & Dillenbourg, 2000; Zumbach & Reimann, 2002) to enhance authenticity as well as transfer. The major rationale of these approaches is to integrate learning goals within scenarios and to use hypertext information access to support information seeking processes during problem solving. This gives hypertext learning a meaningful framework and should enhance learners' motivation by decreasing oversimplified learning scenarios and providing complex learning environments (note that the term "complexity" here addresses the complexity of the content or a domain and not the complexity of language that is addressed as another relevant issue in a following part of this article).

CFT and the integration of hypertext learning resources into a broader learning context represent two major approaches of hypertext learning applications and underlying research. Leaving the area of application in order to analyze basic processes of hypertext, reading comprehension is another major focus of past and current research. In this domain, the primary promising suggestions of hypertext or hypermedia (1) use in classroom or college have to be revisited. A decade ago researchers such as Berk and Devlin (1991) have stated that: