Figure: Remote collaboration in NICE enabled via avatars.
Both technical and educational design issues were taken into consideration in the process of developing NICE. The main areas of development presented below include constructionism, collaboration, narrative, the user interface, persistence, and intelligent agents.
3.2.1. Constructionism
The approach to constructionism taken by NICE echoes Papert's ideas in two ways: first, the learners can craft the environment within the virtual world (construction inside the VR environment), and second, the children can construct something meaningful to them.
The form of construction originally conceived for the NICE environment resembled the ``incredible machines'' or the Lego projects at MIT. Children can understand how complicated machines can be by constructing them. The environment provides the primitives, building blocks, or raw materials, as well as compositional rules for these objects. Although the rules include a well structured set of semantics for the behavior of each object, the objects should have separate structure from function; otherwise they would be overloaded with functions. Attached to each object is a description of its physical structure. The functionality of the object is not in the object itself. An object can be made to interact by being selected or brought into physical proximity. It is the person that interacts with it that constructs the affordances of the object.
Some of these thoughts have been implemented in NICE but not to the level of building blocks. In the garden one can shrink, jump, select and plant, but cannot construct from primitives. While other VR projects support ``world-building'' activity, the construction takes place outside of the virtual space. It is a technical challenge to provide a construction environment within virtual reality. The focus has thus moved to the construction of the underlying ecological models from within the virtual world through end-user authoring techniques. Learners may work in a ``greenhouse'' to qualitatively specify plant growth rules or isolate individual controlling variables. In NICE, the garden itself is the artifact, the object that the children design on their own. Additionally, a more physical product of the interaction with the virtual space, is the story published on the web page.
3.2.2. Collaboration
The construction of the environment may be in support of fostering the collaboration. Our goal in NICE is to promote social interaction. As with the Graphic StoryWriter \cite{Steiner92}, learning environments may teach interaction and social skills in an implicit way. In the case of virtual reality, additional opportunities for the support of role differentiation are afforded but additional issues also arise. Each person has a mental model of the other person and the world. How does the mental model change when one can not see the person? What do you do when other people don't behave the way you expect?
The physical structure of the CAVE offers the advantage of supporting a group of users that can experience the virtual world simultaneously. Support for remote collaboration has been achieved in NICE through the use of networking and the representation of participants as avatars. The avatars handle a wide range of gestures that allow close-to-real-life communication (\ref{figavatars}).
Figure: Remote collaboration in NICE enabled via avatars.
3.2.3. Stories
Of great interest in NICE has been the development of a narrative environment that would support multiple, resumable, infinite, interesting, and evolving stories. This could mean a complex story or many story threads which do not limit the participants to having a single overall set of goals or a single storyline. What is important is the potential for stories with a loose goal that give the freedom to the user to create closure or leave it open. Creativity and ingenuity are more engaged by open-ended situations where conclusions cannot be foretold.
The problems with narrative in synthetic environments have been noted by others \cite{Bates92,Maes89}: Where is the story represented? Is there a database or are there rules? Is there a general central definition of the story? Do you need a director? Is there a moral to the story? Is the moral something we can build or, for example, will the selection of the characters define the moral? An idea for defining a personal story is to have the user choose an initial set of characters and objects to interact with. This is a subset of a larger set and does not have to be the same every time. It can be removed or misplaced by the user. Thus the child crafts the story by selecting the initial state of the world. There are also standard objects, embellishments, or requirements loaded by the designers from the start. The rule base operates with these two subsets to provide stories that will require problem solving.
The story in NICE is the long-term multiparticipant environment. In essence, our manifestation of story in NICE follows the stories created by emergent writers. Children typically advance from telling list-like stories to more complex and easily recognizable stories \cite{Applebee78,Steiner92}. The story that the NICE system outputs now is much like the first. The narrative action in the CAVE is captured through a simple transcript generated by the system. The transcript is automatically published on a WWW page after passing through a simple parser which replaces some of the nouns in the text with their iconic representations (\ref{figstories}).
Figure: The WWW story generated by the NICE system.
3.2.4. User Interface
In a learning environment, the interface assumes special importance. Engagement of the user at the level of the interface takes on special importance in the case of virtual reality, as the goal is to induce the participant's complete and willing suspension of disbelief. The main issue is how to build a simple, familiar interface to a complex environment. In the case of NICE, the challenge is in supporting all the actions, especially the construction aspect, with an interface that is natural, flexible, and easy for use by children.
To support multiple actions in VR, various techniques have been used by researchers. The user may have the ``Midas touch'' or wear ``smart costumes'' \cite{Laurel94}. When touching an object it can change colors or functions, or the participant may wear different coats to perform different actions, such as the ``move'' coat, the ``scale'' coat, the ``rotate'' coat and so on. Also important in VR is spatial orientation, to provide the children with a ``sense of place''. In the real world, people are known to leave marks to orient themselves. Brenda Laurel (1994) extends this idea with the virtual equivalent of footprints, graffiti, shadows, or planting flags on the moon.
The NICE world includes several features to enhance the interface. At the level of the hardware, efforts have been made to replace the wand, the CAVE's main interaction device, with a more natural interface method, such as a dataglove or physical gardening tools. Currently we utilize the wand, using all three buttons for the simple actions and the joystick for moving. The virtual world includes the representation of the child's hand holding the wand. Attached to the hand is a small menu as a reminder of the button functions, and a virtual pointer to aid picking and navigation. Visual and audio feedback mechanisms are provided: every object that can be selected is surrounded by a yellow balloon and the plants indicate their state by displaying umbrellas or wearing sunglasses (\ref{figfeedback}). The children can also view their reflection on the surface of the water surrounding the virtual island.
Figure: Visual feedback cues for interaction in NICE.
3.2.5. Persistence
An area we are greatly interested in exploring is the notion of never-ending virtual worlds. That is, virtual worlds that continue to exist and interact either with other participants or intelligent agents, even when no one is currently in the world. This allows users to enter a virtual world, work on extended tasks that may take some time to complete, and have the opportunity to continue at another time. This is significant in terms of learning, as the ideal uses of learning technology should not be episodic but involve a voluntary and longer-term commitment, not an isolated short experience. Challenging issues involve the depiction of persistence: how will the users know that the world has evolved, how will they view what has happened during their absence?
The idea of persistence is constantly being developed in NICE. The garden itself evolves just like a real garden; if it is not tended, the plants grow old and weeds take over. The design of the system is such that it allows the parts which include behavior to operate without running the virtual environment.
3.2.6. Intelligent Agents and Actors
The children entering a virtual world can have an experience that is loosely predetermined: they may choose their level of participation by taking a leading role or not, use their physical abilities, or extend them. The experience involves the world, objects, and other characters, either remote, proximate, real, or artificial. Ideally, smart agents can be active participants, serve as directors, and be capable of picking and manipulating objects, just like real people. Their behavior and interaction can be described through scripts or evolve autonomously, depending on the degree of intelligence.
With respect to learning, artificial characters may be guides or ``mentors'', facilitating the teacher by taking on the load of more automated tasks. Moreover, children with higher levels of communication apprehension may be more comfortable talking to a synthetic, fantasy creature, which may be anthropomorphic but not a real human. They can communicate and act without the fear of a critical adult or teacher.
The developments of Artificial Intelligence in the area of autonomous artificial agents have not reached a level to achieve the flexible, responsive behavior required by a learning environment. For this reason, the ``agents'' and characters in NICE are still real people disguised by their avatars. This technique is called Wizard of Oz \cite{Wilson88} and has been used in other learning projects and VR worlds \cite{Laurel94}, adding the value of performance and aiding the study of social issues.
The NICE project is continuously being expanded to include many of the
above ideas. The goal is to create a testbed application that
explores and exemplifies these principles in an educational context.