How many times you have seen an error message window to pop-up in an application giving you a meaningless error message and all you can do is to press “Ok” or “Cancel” without any idea where the error message was related to. At best the error message gives you some hint what was wrong and you may get back on track with the application. However once you close the pop-up, you no longer have the details of the error message to help you with fixing the problem. Do the applications you yourself have developed behave this way?

Well, things don’t have to be this way? On the contrary, you as a developer should design applications so that you never let your users to find  themselves in situations like this. It’s not only a benefit of the user, but also a benefit of you as a developer. Once your applications works fluently and gives your users intuitive feedback, you need to spend much less time for the user support and you’ll have much more time for your most important tasks.

One way to increase the usability of your application is to avoid pop-up windows altogether and instead display contextual error-messages in-place as close to the actual point-of-problem as possible. For example, when you have a user editable string control, your application should display the error message right next to the string control and instruct the user right away fix the problem occurred.

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User interface may be the one most important part of your LabVIEW application. It’s the only part of the application the end-user is directly in contact with. Still user interface is often the part of a LabVIEW application developers spend the least time with in the development process. Does LabVIEW make creating decent user interfaces too easy to be ignored in the design phase?

User roles

Let’s concentrate on graphical user interfaces. What should a user interface design process be like? The user interface design shoud start with determinig the different user roles of your application. For example you may need to have a different kind of user interface for the end-users as you do for the administrators.

Views of your user interface

After you have indetified different user roles you should list the main tasks a users in different user roles uses your application. It’s important not to go into too much detail, just concentrate on the most important tasks. The number of main tasks depends on your application. Determine what kind of views do you need in your application to allow users to do these main taks you have identified. You may need multiple different views such as monitoring view and configuration view and visualization view. Depending on your application, these views may be separate parts of a single window, different states of a window or separate windows.

Paper mock-ups

Once you have determined the main views you’ll need in your application you should not hurry to your computer and start coding. Instead you should sit down, take you pen and paper and start drawing mock-ups of your user interface. A mock-up is a model of you user interface. With pen and paper it’s easy and fast to try different variations of component locations. Also the drawing process helps you to concentrate on the important parts and not to go into too much detail too soon. You identified different main tasks the users need to do with your application. Go trough these tasks with your paper mock-ups. If there are major state changes in your views, don’t spare the paper. Try to cover all important views of you application and all important states of different views. Play around, all time consumed in the paper user interface design phase is well spend.

Usability testing

Next you should grap a small group of potential users and show them the user interface mock-ups you have made. Users tend to think differently from what you expect so it’s important to get into direct contact with the potential users. Show them your user interface paper models and ask them to proceed with the important tasks. Don’t help them too much, let them figure out by them-selves what to do, which button to press. Simulate the user interface functionality by showing them different pieces of paper. Use your imagination to find a nice way to simulate your user interface without a computer. Again, don’t go into too much detail, concentrate on the most important parts. If your test users don’t behave the way you would expect them to, ask them what would be the intuitive way for them to proceed with the tasks.

Hand drawn paper user interface models are an excellent tool for the user testing. In computer graphics based user interface models, the tested users tend to concentrate too much on the details and on the lack of polishing. With hand drawn paper models it’s evident that they are only models and users don’t expect them to be polished. Instead they concentrate on the usability and that is exactly what you want to test with them.

Don’t be afraid with the user test phase. You can really often find suitable test persons from your work or from your friends. Testing your user interface doesn’t take a lot of time but you get plenty of valuable feedback. With this feedback you need to go back to your desk and start considering how to make your user interface better, how would it serve your users better.

Conclusions

User interface design is an iterative process. Depending on the complexity of your user interface you may need to iterate the process several times. Only after you are happy with your paper models, you should start working on real front panel implementations. There are many ways of designing user interfaces and this particular process I learnd from useability experts when working on a consumer product project.

Take a look at Jim Kring’s related post on Human Interface Guidelines on his blog Thinking in G.