Visitadores, visitas y obstáculos

Hypertext and Hypermedia systems are increasingly used in educational environments even if their efficiency is not clear enough [Jon 1990]. The active participation of readers and authors is generally supposed to be the major advantage of hypertext systems (e.g., [Lan 1992]). There is some evidence from cognitive psychology that supports this assumption. A deep processing and

elaboration usually leads to better comprehension than an information analysis at higher levels of processing. One way of reaching these deep processing levels is by "doing things" [May 1992]. However, an active involvement of learners does not mean letting them browse in a hypertext base aimlessly. Students must be encouraged to actively seek out information. This can only be achieved by giving well-defined tasks to students [Ham 1992].

The idea of education based on learning more than on teaching has intrigued cognitive psychologists and educators. They have studied the ways in which people learn in order to find the best ways of presenting knowledge which could be used in developing materials for individual interactive learning. It has been shown that it is easier to learn and remember material presented in graphical form, and when learning, it requires more activity on the students’ behalf [Bar 1990]. Another way of learning is through goal-based scenarios. The teacher sets the learning goals and each student researches the subject in his or her own way, discussing it later with colleagues. In this way students are more mentally involved, which results in better understanding and learning of the material.

Some studies have shown that the use of hypermedia, besides improving student motivation, also improves students' ability to make their own cognitive connections, handle large amounts of information, use critical, relational thinking, participate in class discussions and their ability to read [Cos 1994].

According to Szuprowicz [Szu 1992], what makes the use of interactive multimedia courseware in education particularly attractive is the

"individualization of instruction, self-paced exploration of knowledge, experimental learning, and instant and effortless performance measurement."

This helps to develop new ways of thinking and drawing conclusions for the students who use interactive multimedia. The visible advantages of interactive multimedia depend on how the courseware is adapted by students. It has been expected that the use of interactive multimedia in schools will grow because of the above advantages, as well as because of the drop in the cost of hardware and multimedia software.

Pereira, de Oliveira and Vaz [Per 1991] maintain that a hypermedia system for education should contain three significant components, a text database (and other media), a semantic network which interrelates the database components and enough tools to allow the user to explore the database and the semantic network. The authors of hypermedia domains should generate only few closely interrelated links instead of linking to anything, so that the user may navigate using the “pseudo hierarchical structure” known as “cognitive scaffolding”.

Jonassen and Grabinger [Jon 1990] suggested that a hypermedia system can be defined as a network of ideas. The linking structure of the ideas helps improve user comprehension of the node content. Such a structure is suitable for learning, due to the similarity between the associative structure of hypermedia and the associative structures existing in the human brain:

“The belief that hypertext can mimic human associative networks implies that an appropriate method for structuring hypertext is to mirror the semantic network of an experienced or knowledgeable performer or expert” [Jon 1993-2].

The knowledge structures are transferable from the hypermedia to the learner; however, simply browsing through a hypermedia system is not enough to produce any appreciable transference of structural knowledge. Moreover, it is necessary to provide exercises that explicitly test the learner's structural knowledge of the domain. Information may be considered as stored in the brain in an associative manner, thus information is linked together to form a network of knowledge. Such a structure is referred to as a "schema", and each one has a number of attributes that enable it to be linked to other knowledge structures. The process of learning is the acquisition of such information schema and arranging them into the learner’s knowledge structures.

Jonassen [Jon 1993-2] stated that three processes allegedly govern learning: accretion, restructuring and tuning.

Accretion is the process of adding information to existing schemas, i.e. new content is added with links to other existing schemas.

Restructuring occurs when a schema has been expanded to a point where it is no longer viable. Additional schemas are then created from the existing schema and the new knowledge which allows the learner to access and interpret the existing knowledge in new ways.

Tuning is the process of making small adjustments to the schema while it is being used, i.e., with practice, the learner becomes better at using the knowledge.

A useful hypermedia structure would therefore be a representation of the knowledge schema of an expert. The learner attempts to map these structures onto their own, using the hypermedia. This transferral of structure, from the hypermedia to the learner, represents a challenge to hypermedia designers. It is necessary to set up an adequate structure so that the learner will have sufficient cues to incorporate the information into their own knowledge structures.

“The less structured the hypermedia is, the less likely users are to integrate what they have learned into their own knowledge structures, because the hypermedia facilitates only the acquisition part of learning” [Jon 1990].

The above discussion suggests therefore that structural information is paramount for an educational system.