Thoughts on Design

There is a book I am currently reading (and recommend): “The design of everyday things” by Donald A. Norman. The author describes common design errors in an easy readable way and shows or outlines the solutions for them. Despite not beeing a book about software engineering, it covers pretty well one of its greatest problems: interaction with a human. What are the points a software developer should consider when creating new or changing old features?

Natural mapping

Natural mappings are the clues that we can map to known patterns and instinctively use to interpret new unknown things. These mostly date back to prehistoric times and address the animal in us to catch our attention. To animals big things, moving things, things that are different because of color, shape or some other distinctive property are important, because they must decide based on them whether to flee or to attack. Natural mappings require near zero conscious processing power and make the user to pay attention to crucial information instantly. If you have two buttons “cancel order” and “submit order” and you want the user to click on submit, you better make the submit button big and flashy and the cancel button normal size and color it in standard grey (Have a look at the publish button and the preview button of wordpress).

Visibility

Not all users read the manual (if any exists) before they use their programs. Not all users that read the manual, can understand it or find there the steps necessary to accomplish their task. To be still able to succeed, at every step the user asks himself the following questions:

  • What is already done?
  • What is my current position in the process?
  • What is to do now?
  • How far I am away from my goal?

Consider a user who only has 15 minutes and has to fill out an order form consisting of 15 pages. A user who does not even get the total number of pages stops frustrated after very few pages, because the process seems endless. Provide him with the page count and the current page and he will be able to plan ahead and esimate the needed time. If the mandatory fields are marked, the user will concentrate on them and progress faster, incresing the probability to complete the order in time.

Feedback

Every time a user has done something, he will want to ensure that everything happened as he wanted. A mute system will inspire confusion and fear (Want to try it out? Use ed). A status message is a great signal for the user that he accomplished some of the steps on the way to his goal. Without the message “Order submitted successfully” the user won’t know whether the system accepted his input or just jumped to an another page. Additional confirmations like emails allow the user to receive status information with the additional benefit of being persistent unlike a web page in a browser.

Errors

Like any human the users input bogus data or trigger unwanted actions. In this cases the user should get appropriate feedback. When the previous steps are considered, the user will know what field is affected, why the input is not accepted and what the steps are to correct the situation. Sometimes the errors are logical and not syntactical, making them hard to impossile to detect by the system. There is no way to tell whether the user wanted to buy one or ten books. The layout of elements can be adapted to minimize the risk of accidental use: the “Close Application” button is better not to be placed near the “Save” button. When the mistake has been done, the user should be offered an edit, or at least a withdrawal option. Not all systems allow reversal of actions, and present the user a confirmation dialog with an important choice, producing unnecessary stress. There are ways to conter that problem.

Conclusion

This are simple points that can be taken into consideration when carefully designing a system. Even if they are simple, we tend to forget them because we have deadlines or understand the system on such level that we cannot even imagine what steps an inexperienced user can take and what hints he need.

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