The Goal: To explore alternatives and trade-offs in the design of a single graphical interface component.

The Scenario: The switches we flip back and forth to turn the room lights on and off, and the push buttons we press to power appliances up or down, are just two examples of so-called toggle switches in our physical environment. The same interaction mechanism is found in today's mouse driven graphical user interface, for example the buttons with which we select and deselect bold, italic and underline styles in Microsoft Word.

Although the displays used nowadays on most computers serve only as an output device, touch screens which support both input and output may be the wave of the future. While the utility of such hybrid components in hand-held devices is clear, they are widely used as well in large-screen "information kiosks" and interactive exhibits at many museums, as well as "home automation" systems which support computerized setting of major appliances and climate controls in modern upscale dwellings. Typically, in the latter application a screen located in a convenient spot displays the current settings of all the devices which have been linked into the system; the homeowner uses on-screen toggles to turn them on and off at will, and other widgets such as sliders to adjust their settings. In these and similar applications, toggle design may influence how easy it is for users to operate the system. It is reasonable to assume that not all possible designs for toggles will prove equally satisfactory.

What To Do: In this exercise our goal is to see how many different designs for touch screen toggles--as a component of a "conventional" graphical user interface for a home automation system--we can come up with. The idea is to focus not on minor variations in color or shape, but rather on qualitative distinctions in functionality--that is, your various designs should in some sense work in different ways. I don't want to say more so as not to constrain your thoughts in any preconceived directions.

Divide up into teams of 4-6 members each, and rearrange seating as necessary so as to facilitate interaction among team members. Begin by thinking about the appliances in your home, in your dorm room. What do the toggles used there look like? What might their counterparts in the graphical computer interface look like? Now add to your initial collection of designs by recalling other kinds of toggles you've seen in computerized systems or in the physical world. Feel free to also make up new alternatives that you've not previously seen anywhere. In all cases, are there any special considerations or problems you foresee for somebody implementing your designs? For somebody using your designs? If so, think about what they are and how they might be overcome. Which of your designs do you think users would probably prefer, either due to appeal or greater efficiency? Why?

Feel free to discuss whatever you wish with me during the period, if your team encounters issues or problems you're unsure how to resolve. Towards the end of the session, I will call for volunteers from the various teams so we can gather the many different designs we've come up with as a group. We will try to collectively agree on a ranking for our designs according to potential user preference, and finally we will view a short video of an experiment conducted a few years ago at the University of Maryland on this topic, to compare our designs and predictions against their findings using actual subjects.

As usual, after the conclusion of the in-class part of the exercise your team should summarize its designs and the lessons learned in a written report which includes diagrams and illustrations as needed. Discuss what you perceive to be the advantages of each of your designs, and also possible problems. The report (one copy with all team member names listed) is due ten days after the in-class phase of the exercise is completed.