Previous Table of Contents Next


This chapter describes the entire three-part methodology that is the bridge over the gap between user needs and GUI design prototype, being most thorough in describing the center span — Part 2, Task Object Design.1 We set the stage by describing the Bridge methodology’s broad context within a sequence of other methodologies that cover GUI design projects from start to finish, and give an overview of the explicit steps of The Bridge itself. Then we describe some of the techniques and orientations that pervade, underlie, and are the medium of its three explicit steps. Finally, we describe those explicit steps in more detail. Before all of that, let’s get a feel for the atmosphere and dynamics of Bridge sessions.


1The full methodology has not yet been fully described in any generally available publications. The most complete description other than this chapter is handed out as notes when the methodology is taught in all its breadth and detail, for a consulting fee. Portions of the methodology have been taught at conferences such as UPA (Dayton and Kramer, 1995, July; Kramer, Dayton, and Heidelberg, 1996, July), OZCHI (McFarland and Dayton, 1995, November), CHI (Dayton, Kramer, McFarland, and Heidelberg, 1996, April), APCHI (Kramer and Dayton, 1996, June), and HFES (Dayton, Kramer, and Bertus, 1996, September).

1.1. A TYPICAL SESSION

The Bridge methodology uses a participatory session as its primary medium. Every session is somewhat unique, there being many dimensions along which a session exists. For example, sessions typically last 3 days but for large complicated projects can last 7 days. To give you a flavor before we get into the details of those variations, here is a short story of a typical session:

Monday begins with the two facilitators directing the five participants (expert user, novice user, usability engineer, developer, system engineer) to the five seats at a small round table. The facilitators briefly explain the session’s goals and approach, and lean into the table to start the group writing the Big Picture index cards. Within a few minutes the participants themselves are writing task steps on cards and arranging the cards into flows on the blank flip chart paper in the table’s communal center. After push-starting the group, the facilitators fade into the background, floating around the edges of the table and becoming most noticeable when introducing each step of the methodology. Within the first half day the five participants have become a well-functioning team and feel that they are running the session with only occasional help from the facilitators. The atmosphere is fun, sometimes goofy, with periodic showers of paper as discarded index cards and sticky notes are torn up and thrown over shoulders. At the end of Monday the walls are covered with the task flows that were created on the table. Each flow is composed of a set of index cards connected with sticky arrows, all attached with removable tape to a piece of flip chart paper (see Figure 2.1 left side). Commentaries are stuck on top of the task flows in a riot of fluorescent stickies of assorted sizes and shapes.

By lunch time Tuesday the table holds an additional dozen cards, each having stuck to its lower edge a sequence of blue, pink, and yellow sticky notes (top right of Figure 2.1). The team designed those dozen “task objects” to represent the units of information that are needed by users to do the task flows posted on the walls. The floor is littered with an additional dozen cards that were discarded as the team refined its notion of what information qualifies as a task object. The team has verified that the set of task objects is usable for doing the tasks, by walking through the task flows while checking that there exists a task object listing both the data and the action needed for each task step.

Up to now the facilitators have banished the GUI from the conversation, to keep the participants focused on the abstract task and its units of information. However, after lunch on Tuesday, the facilitators give to the participants photocopies of GUI windows whose client areas and title bars are blank. Participants make a window for each task object by hand drawing some of the attributes from the blue sticky of that task object into the client area of a window (bottom right of Figure 2.1). By the end of this second day only eight of the original task objects remain on the table, the participants’ notion of objecthood having been refined by their act of translating task objects’ attributes into window views.


Figure 2.1  The three types of artifacts resulting from the three consecutive parts of The Bridge methodology. Part 1 yields a set of hand-lettered index cards and removable sticky arrows representing task flows. Part 2 extracts task objects from those flows and represents them as hand-lettered index cards with removable sticky notes. Part 3 expresses each task object as a GUI object, usually as a window; the window contents are hand drawn on photocopied empty windows.

Wednesday starts with participants drawing additional paper windows to represent additional views for some objects’ attributes. After the coffee break comes the first GUI usability test. The facilitators use masking tape to delineate a computer screen as a big empty rectangle on the table. A user points and clicks with a finger within the rectangle, the other participants serving as the computer by adding and removing paper windows as dictated by the user’s actions. As the task flows on the wall are executed in this way, the team discovers flaws in the paper prototype, revises the prototype and the task objects, and resumes the test. At the end of this third day the team does another usability test, this time with windows to which the team has added menus and buttons as GUI expressions of the actions that were listed on the task objects’ pink stickies. There are only four objects left. The usability engineer walks away Wednesday evening with a usability-tested paper prototype of the fundamental GUI design (bottom right of Figure 2.1).


Previous Table of Contents Next