15.7 DESIGN MODELS AND METAPHORS

Developing design models and design metaphors will be an important aspect of theory-building, research, and development(see also 7.2) in the emerging virtual reality medium. A few models and design metaphors have emerged that are specifically for education and training.

Wickens (1993) and Wickens and Baker (1994) have proposed a model of virtual reality parameters that must be considered for instructional design. These analysts suggest that virtual reality can be conceptualized in terms of a set of five features, which are shown in Figure 15-5. Any one of these five features can be present or absent to create a greater sense of reality. These analysts suggest that, based on these five elements, several justifications can be cited for using virtual reality as an educational tool. These justifications include: (1) Motivational value; (2) Transfer of learning environment; (3) Different perspective; and (4) Natural interface. According to Wickens & Baker (1994, p.4),

We may conceptualize the features of VR in terms of two overlapping goals: that of increasing the naturalness of the interface to reduce the cognitive effort required in navigation and interpretation, and that of creating dynamic interaction and novel perspective. It is important to keep the distinctions between these goals clear as we consider the conditions in which VR can facilitate or possibly inhibit learning. Specifically, we argue that those features of an interface that may reduce effort and increase performance, may actually reduce retention.

Figure 15-5. Five components of virtual reality. (Adapted from Wickens & Baker, 1994.)

1. Three-dimensional (perspective and/or stereoscopic) viewing vs. two-dimensional planar viewing. Three-dimensional viewing potentially offers a more realistic view of the geography of an environment than a 2-D contour map.
2. Dynamic vs. static display. A dynamic display appears more real than a series of static images of the same material.
3. Closed-loop (interactive or learner centered) vs. open-loop interaction. A more realistic closed-loop mode is one in which the learner has control over what aspect of the learning "world" is viewed or visited. That is, the learner is an active navigator as well as an observer.
4. Inside-out (ego referenced) vs. outside?in (world referenced) frame of reference. The more realistic inside-out frame of reference is one in which the image of the world on the display is viewed from the perspective of the point of ego reference of the user (that point which is being manipulated by the control).
5. Multimodal interaction (enhanced sensory experience). Virtual environments employ a variety of techniques for user input, including speech recognition and gestuyes, either sensed through a "data glove" or captured by camera. reality may accomplish this reduction. Some of these features, like the naturalness of an interface which can replace arbitrary symbolic command and display strings, clearly serve the goals of both. But when effort?reduction features of virtual reality serve to circumvent cognitive transformations that are necessary to understanding and learning the relationships between different facets of data, or of a body of knowledge, then a disservice may be done (p. 17).

Based on this model, these analysts discuss the cognitive issues involved in using virtual reality for task performance and for learning applications. They suggest that virtual reality may prove useful for four types of educational tasks: (1) on-line performance; (2) off-line training and rehearsal; (3) on-line comprehension; and (4) off-line learning and knowledge acquisition. These four categories, and the examples of each category that the authors present, clearly reflect emerging training needs linked to high technology, as well as more traditional training needs.

On-line performance refers to systems where the virtual environment is providing the operator with direct manipulation capabilities in a remote, or nonviewable environment, for example, the operation of a remote manipulator, such as an undersea robot, space shuttle arm, or hazardous waste handler, the control of a remotely piloted vehicle, or the task of navigating through a virtual data base to obtain a particular item. Wickens and Baker (1994) suggest that three general human performance concerns are relevant in these environments: (a) closed-loop perceptual motor performance should be good (that is, errors should be small, reactions should be fast, and tracking of moving targets should be stable); (b) situation awareness should be high; and (c) workload or cognitive efforts should be low.

Concerning off-line training and rehearsal, Wickens and Baker (1994) suggest that virtual environments may serve as a tool for rehearsing critical actions in a safe environment, in preparation for target performance in a less forgiving one. According to Wickens and Baker (1994, p.5),

This may involve practicing lumbar injection for a spinal or epidural anesthesia, maneuvering a space craft, carrying out rehearsal flights prior to a dangerous mission, or practicing emergency procedures in an aircraft or nuclear power facility. The primary criterion here is the effective transfer of training from practice in the virtual environment to the "true reality" target environment.

In terms of on-line comprehension, Wickens and Baker (1994) explain that the goal of interacting with a virtual environment may be to reach insight or understanding regarding the structure of an environment. This type of application is particularly valuable for scientists and others dealing with highly abstract data. Finally, off-line learning and knowledge acquisition concerns the transfer of knowledge, acquired in a virtual environment, to be employed, later in a different more abstract form (Wickens & Baker, 1994).

Wickens (1994, p.17) cautions that:

The goals of good interface design for the user and good design for the learner, while overlapping in many respects, are not identical. He points out that "a key feature in this overlap is the concern for the reduction in effort; many of the features of virtual reality may accomplish this reduction. Some of these features, like the naturalness of an interface which can replace arbitrary symbolic command and display strings, clearly serve the goals of both. But when effort-reduction features of virtual reality serve to circumvent cognitive transformations that are necessary to understanding and learning the relationships between different facets of data, or of a body of knowledge, then a disservice may be done.

Wickens also recommends that these design considerations should be kept in mind as virtual reality concepts are introduced into education. Also care should be taken to ensure redundancy of presentation formats, exploit the utility of visual momentum, exploit the benefits of closed-loop interaction, and use other principles of human factors design.

Wickens (1994) recommends that related human factors research concerning the characteristics of cognitive processes and tasks that may be used in a virtual environment should be taken into account. These factors include task analysis, including search, navigation, perceptual biases, visual-motor coupling, manipulation, perception and inspection, and learning (including procedural learning, perceptual motor skill learning, spatial learning and navigational rehearsal, and conceptual learning). And Wickens suggests that there are three human factors principles relevant to the design of virtual environments --- consistency, redundancy, and visual momentum --- which have been shown to help performance and, also, if carefully applied, facilitate learning in such an environment.

A design metaphor for representing the actions of the VR instructional developer has been proposed by researchers at Lockheed (Grant, McCarthy, Pontecorvo, & Stiles, 1991). These researchers found that the most appropriate metaphor is that of a television studio, with a studio control booth, stage, and audience section. The control booth serves as the developer's information workspace, providing all the tools required for courseware development. The visual simulation and interactions with the system are carried out on the studio stage, where the trainee may participate and affect the outcome of a given instructional simulation. The audience metaphor allows passive observation, and if the instructional developer allows it, provides the trainee the freedom of movement within the virtual environment without affecting the simulation. For both the instructional developer and the student, the important spatial criteria are perspective, orientation, scale, level of visual detail, and granularity of simulation (Grant, McCarthy, Pontecorvo, & Stiles, 1991).