Hypertext refers to a collection of documents containing links that allow readers to move from one chunk of text to another. Hypertext may increase cognitive load relative to the processing of regular text.
Cognitive load consists of mental load, mental effort and performance. Working memory refers to the set of mental resources that people use to encode, activate, store and manipulate information while they perform cognitive tasks. Increased mental load is associated with reduced performance in hypertext reading. Executive functions include decision making, coordination of task demands and inhibition of irrelevant information.
Situation models refer to complex mental representations formed when readers integrate the statements in the text with their knowledge. The interruption of going from one hyperlink to another may have minimal effects on comprehension if the next text is related to and enhances the developing situation model.
It is possible that interruptions in reading impair situation model formation. Learning tends to be better when there are fewer links in a hypertext. Increasing the number of links may increase cognitive load and impair learning.
Networked hypertexts may impair a reader’s efficiency navigation. In general, the more links, the slower the navigation will be. It seems that people perform best when there are a lot of choices in the introductory screen and fewer choices at deeper levels of the hierarchy. A hierarchical structure of a test generally helps navigation.
Readers with low working memory spans benefit from structured texts and from organizers that highlight text structure. Hypertexts may be less appropriate for low working memory span readers. Individuals who are poor at keeping verbal representations active in memory may be disadvantaged because related sentences may be spread further apart in non-hierarchical hypertexts.
The flexibility of hypertext may be beneficial for readers who are positioned to structure their own learning activities (e.g. readers with prior knowledge, readers with an appropriate learning style). A flexible cognitive style (i.e. neither strongly analytic or wholistic) may be beneficial when reading texts with semantic links. The ability to monitor and organize one’s own learning becomes more important when hypertext structures are more demanding to process. Making the learning task harder by requiring readers to structure the text may have benefits for some learners whereas the increase in difficulty may overwhelm less able learners.
High knowledge readers do not necessarily benefit from hypertext as compared to low knowledge readers. Low-knowledge readers might benefit from hypertext that transparently conveys the structure of the text content.
Link previews might help provide context for the destination information, activating existing concepts in the reader’s knowledge structure and enabling integration. Labelling links can also enhance navigation performance. Mentally preparing to integrate information of a certain type can enhance comprehension and decrease cognitive load.
The prior knowledge of the reader influences the usefulness of structural overviews. High knowledge readers can rely more on prior knowledge and thus may be less affected by the way the text is presented.
When overviews are visually complex, the increase in cognitive load required to use the overview may detract from the overall processing in a limited-capacity system. Innovative and complex overview styles may only be appropriate when the learner is expected to interact with the information over many sessions.
The availability of explicit information about the text’s structure may decrease the reader’s motivation to form an internal mental representation of the structure. Organizing materials in a way that encourages people to explore a related set of texts before moving on to another set may help people to form situation models.
