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The objects to which actions apply.

Information or attributes that each object in the task must preserve, display, or allow to be edited.

Identify the objects and actions that appear most often in the workflow.

Make the several most important objects very obvious and easy to manipulate. All objects that have to be manipulated to get work done must be clearly described.

Their behavioral characteristics must be established and the attributes that differenti- ate each kind of object must be identified. Relationships of objects to each other and the people using them must be determined. The actions people take on objects must also be described. Information or attributes that each object in the task must preserve, display, or allow to be edited must be defined.

The most important objects must be made very obvious and easy to manipulate. Weinschenk (1995) suggests that if the most important objects are not obvious in the workflow, go through the workflow document highlighting all nouns and verbs asso- ciated with nouns. Frequently appearing nouns are possible major objects. Frequently appearing verbs are actions pointing to possible major objects.

Developing Metaphors

Choose the analogy that works best for each object and its actions.

Use real-world metaphors.

Use simple metaphors.

Use common metaphors.

Multiple metaphors may coexist.

Use major metaphors, even if you can’t exactly replicate them visually.

Test the selected metaphors.

A metaphor is a concept where one’s body of knowledge about one thing is used to understand something else. Metaphors act as building blocks of a system, aiding understanding of how a system works and is organized. Select a metaphor or analogy for the defined objects. Choose the analogy that works best for the objects and their actions. Real-world metaphors are most often the best choice. Replicate what is famil- iar and well known. Duplicate actions that are already well learned. If a faster or better way exists to do something, however, use it. Use simple metaphors, as they are almost always the most powerful. Use common metaphors; uniqueness adds complexity. Multiple metaphors may coexist. Use major metaphors even if you can’t exactly repli- cate them visually on the screen. Exactly mimicking the real world does not always aid understanding. It can lead a person to expect behavioral limitations that do not actu- ally exist. A representation will be satisfactory. Finally, test the selected metaphors. Do they match one’s expectations and experiences? Are they easily understood or quickly learned? Change them, if testing deems it necessary.

A common metaphor in a graphical system is the desktop and its components, items such as folders and a trash can. The Web utilizes a library metaphor for the activities of

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stacks looking for something interesting to read. When searching, you devise an active plan to find some specific information. For example, first, check the topic in the card catalog. Next, ask the librarian, and so forth.

MAXIM Given a choice between functionally equivalent designs, the simplest design should be selected.

A word of caution in creating metaphors, however. Today’s technology permits doing a lot of things, many not even thinkable in the old manual world (or even the old computer world). Do not be constrained from developing a more powerful inter- face because a current metaphor just happens to exist. If you do limit yourself, you may find yourself in the position of the farm tractor designers of the early last century. In developing a new tractor, the metaphor was the horse and plow. Reins controlled the horse, so reins were installed on the tractor for controlling it as well. Needless to say, it was not successful. We do not want to read about your decision sometime later this century.