The Questions Answered by Navigational Tools

3.2The Questions Answered by Navigational Tools

Where am I?

Where is my destination?

How can I go there?

To answer these questions, the information that helps us identify paths can be received by answering the following questions:

What are the conditions of alternative paths?

Where have I been?

Where can I go next?

Navigation tools also give us information about space itself.

How are objects in space related to each other?

3.3Navigation in Document Space

While document spaces are no less real than physical spaces, they are less likely to be the comfortable four-dimensional space-time we are used to navigating. They may be one-dimensional as is the case for an ordered list or n-dimensional as in the case of a vector retrieval system. A document space may have many presentations. Navigation interacts with such presentation.
The notion of locomotion in a document space is not trivial. Clicking on a link or an icon in the interface, a new display may appear; this may be considered as “go to” or “get it.” Observers may move in a space, or the space may move and change its appearance around observers.
The continuity of motion in a physical space may be not applied in a document space. Jumping from place to place is more common than walking along a continuous path. Traveling in the physical world will be in an egocentric view where an observer is moving in this frame of reference only. The navigation information, such as map recognition or route knowledge, will be transformed and used in this viewpoint. However, in interacting with a program interface, traveling, “go to,” can be done on both egocentric and exocentric views. There are also relative and absolute “go to.” The relative “go to” is when the next location is relative to a current position, while the absolute “go to” does not need a notion of current position. The common desktop metaphor views objects on a display as if the view were from above a desk; navigation does not take place “in” a space but “on” a space.
In physical space, one’s own location is a single point in space. In a document space, it is possible to have many interfaces of radically different types open in multiple windows. For example, Window™ File Manager allows selecting multiple files and opening them. In this case, the navigation metaphor does not fit well. It is a “go to” that involves different places at the same time. One may argue however, that observers still have one central point of focus, at a particular view or window.
As mentioned in the previous section, data spaces may be discrete or continuous and bounded or unbounded. Navigation in a bounded space is easier than in an unbounded space since we know where the edge of the space is. In an unbounded perception space, such as when flying in the sky, or sailing over the sea, or driving on an interstate, intermediate landmarks become important. Feedback of time, location, and distance provides awareness and confirmation that we are not getting lost. While physical space is considered continuous, it has a finite granularity in our perception. Moving in a very small scale and a very large scale at once is uncommon. Discrete navigation may be similar to taking a taxi and giving an address; we may then not be concerned with the specific direction and path which the taxi driver takes as long as we get to the destination.
While navigation in physical space is concerned with place and location, with where to go and how to get there, in a document space, the major concern is information need. The high level goal of navigation is the finding and use of information. According to Jul and Furnas (1997), tasks can be identified as either searching or browsing, and tactics as either querying or navigation. The definitions are given as follows;

“Searching – The task of looking for a known target.

Browsing – The task of looking to see what is available in the world.

Querying – Submitting a description of the object being sought (for instance, using keyword) to a search engine which will return relevant content or information.

Navigation – Moving oneself sequentially around an environment, deciding at each step where to go.” (Jul & Furnas, 1997)
The task and tactics are combined, i.e. searching by querying, searching by navigation, browsing by querying and browsing by navigation.
Navigational activities are classified by Maurer (1996) in the following five categories:

“Scanning: covering a large area without depth.

Browsing: following a path by association until one’s interest caught.

Searching: striving to find an explicit goal.

Exploring: finding out the extent of the information space.

Wandering: ambling along in a purposeless, unstructured manner.” (Maurer, 1996)
In order to navigate successfully in space, one may consider providing perfect tools and information in order to minimize disorientation. Alternatively, assuming it is not possible to prevent errors that lead to becoming lost in space, navigation tools should provide facilities to recover from disorientation. Navigation tools are needed more when we get lost than they are when we know where to go.
Navigation in information space can be accomplished by using an interface, a combination of data presentations and interactions. The knowledge about a space is derived from a presentation and interaction through an interface. To present data from document space in a display, ultimately, the physical dimensions of the display will be used. The object on a screen, representing some data from the document space, takes form somewhere with some attributes of the object. The encoding method and interaction will be discussed later in the next section. There are many ways to encode data into the physical dimensions of the screen and many ways to specify interactions. The encoding on a screen may not encode anything from data; i.e., users may freely move objects on the screen: location is not used for encoding. The screen encoding may be used to encode attributes in one dimension; i.e., objects are spatially displayed in some sorted order. The notion of “place” of presentation may differ from “place” in the document space. The place on the screen can be changed dramatically; the relation of distance between objects may not be preserved while interacting with the interface.
Not only do the data in navigation come from the structure of the document space itself, but they also come from information about where users have been traveling through space, the current position in space, and perhaps from the plan and alternative paths to some other place. Navigation in WWW is considered a recurrent system. There is a 58% chance that the next page will be a page that has already been visited (Tauscher & Greenberg, 1997). However, users visit only a few pages frequently. Many pages are only visited once (60%) or twice (19%).

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