Session 23

Presentation Style


Software Systems

Exercise 34: My Favorite Error Messages

Work in teams of three or four people based on the number in the upper right-hand corner of the assignment page.

As a designer of interactive software systems, I am interested in giving users the best feedback possible. Error messages are an important class of feedback responses. One might argue that they constitute the most important type of feedback, since users who receive them are the ones most likely to be mistaken, confused, and unsure of themselves. Understanding what makes an error message good or bad can help a designer create a better product.

As a group, identify the best error messages and the worst error messages that you have ever encountered as a software user. Accomplish this task as follows:

The tangible result of your work should be (1) a written list of all the messages identified by the members of your group, along with the reasons for their classification based on Shneiderman, and (2) a written list of your two distinguished nominees, along with specific reasons that they stand out among their peers.

Summary of Discussion

The most commonly cited heuristics were

How do you as an audience differ from the typical user audience that Shneiderman is concerned with? Experience, confidence, background.

How do these differences account for the kinds of answers you give? Relatively little, it seems! As an audience, you seemed to want the same sort of support that Shneiderman proposes. Maybe there is something to what he is saying?

The best messages were succinct, clear, and constructive. Some even offered to make the error go away.

The best message award went to the class of messages that tell you what went wrong and how to fix it--concisely. These include:

Honorable mention for the best error messages include compiler messages that take you to the offending expression on a particular line number.

The worst were succinct and cryptic and often revealed some implementation details that you didn't care about.

The worst message award went to the class of messages that tell you a failure has occured, by number, and leave you with no recourse. These include:

Honorable mention for the worst error messages in...

These bad error messages are the remnants of a leftover world, the results of attitudes that formed before personal computers filled every home, back when only real men used computers. Old habits die hard--if at all. We need to work hard to overcome the ruts of our industry.

Exercise 35: Guidelines for the Effective Use of Color

Work in the same teams as you did for Exercise 34.

Once again, I think that Shneiderman provides some nice rules of thumb that may not help me enough when I try to design an interface. Section 11.5 lists fourteen bullets with advise such as "use color conservatively". Okay... So what counts as conservative? Four colors? Three colors? Black on white? When is using more colors appropriate? Well, "when they identify meaningful relationships". Okay... Which relationships are meaningful? What if my system contains so many meaningful relationships that I have to break the number-of-colors rule. As you can tell, I'm confused again.

Your group should be able to produce four or five rules of this sort in the time alloted. You may want to draw on your own experiences as software users and web surfers. Try to recall good and bad examples of web page design, and then try to distill what made them good or bad. Use Shneiderman's list to focus your search.

The tangible result of your work will be a single written list of rule-evidence-exceptions triples. Be prepared for us to discuss and critique your work!

Eugene Wallingford ==== ==== April 3, 2001