This post continues the series User Interface and Products. I recommend reading the first post to get a background on how to define what an interface is and the importance of a good interface to consumers.

Interface Design Process

1. Identify and Empathise with the User

The first step to designing an interface is defining who the core user is. What are their personal characteristics and traits, demographics, what similar products do they use? Sometimes the best solution may not be the most logical one. For example designing a radical new interface for Microsoft Windows might be a bad thing to do as it could cause mass confusion as people are just so familiar with where everything is located. It is imperative to have a deep empathy for the end user. It might be a wise idea to do a roleplay activity and pretend you’re a young child exploring your product for the first time, just to get a great understanding of the inner-physche of your user. This underpins the importance of user testing before a product goes to market.

After empathising with the stereotypical user you must then analyse the outliers of your market, I am talking about the 5th%ile or 95th%ile users who have different needs that don’t relate to the typical user. For example, is your interface design going to facilitate users with a disability, or an older or younger segment within your market? Or do you just ignore these interface needs and limit the market scope of your product?

2. Define and Prioritise the Goals of Your Interface

As mentioned earlier there must be a goal that the user wants to achieve from using your interface. The interface goal of a toaster is to make nice toast, the goal of a cupboard is to store items. But of course not all products are this simple, sometimes we need to give you the user choices of what they may want, or there maybe more than 1 goal the user wants to achieve from your product. Write the goals down of your interface on a sheet of paper and prioritise what is the most important goal or the goal that is likely to be used the most. For example for a printer/scanner it might be as simple as 1. print documents 2. scan documents. Under each goal, list the choices associated with the goal. For example for the goal: 1. Print documents, the choices may be 1. print colour 2. print black and white.

If you want, put percentage data against your goals and choices. For example 90% of the time people print from the printer/scanner and 10% of the time they scan documents; and 55% of documents printed are in colour and 45% are in black and white.

The purpose of this exercise is for you to justify options on your interface. It prevents you from doing the worst thing possible which is over designing an interface by making it inherently confusing to use. It is to prevent you from putting an LCD screen on a toaster with an elaborate menu system and help section for a product that really needs one button. Yes remember the LG Internet fridge.

3. Hierarchically Map Your Interface and Find its Critical Paths

It’s time now to do a full mapping of your interface. Chart the interface using a flow diagram or a mind map. Draw arrows corresponding to the direction the user takeas they explore your interface. The goal should be to get your user to reach his or her goals as quickly and easily as possible. Make sure the critical paths (the path from where your user starts in the interface until they reach their destination goal) is as short as possible. Remember an interface is always finite, it will have a distinct start and finish.

It is important to not get caught up in the technicality of this diagram too much and always refer back to step 1 which is empathising with your user. As you’re mapping this interface have you considered that your user might change his or her mind and go to a different menu item, how are they going to get there? If the user puts in incorrect information how are they going to change it? If the user has to catch a bus and runs out of time to complete the goal activity can they come back and retrieve this information where they left off?

For complex interfaces this mapping can be incredibly difficult and it is a wise idea to do this exercise as part of a small team where collaborative brainstorming may identify path issues.

Part of step 3 is actually designing the interface. This could range from the shape, size and colour of a button, or the positioning of a lever or handle. These considerations and heuristics of this step will be covered in more detail in part 3 of this blog series.

4. Test Your Interface and Refine Issues

After you have mapped out your interface, put it to the test, even if it may seem simple and perfectly resolved. I think the golden rule about interfaces is that if your interface needs a help section or has to display constant error messages, the interface may be suggesting to you that you haven’t done your job correctly. Test your interface on your actual market and get their feedback it will be invaluable to your interface design. If the user has to consult a help section or needs your assistance through the interface, what on earth chance is there that they will adopt your product at a retail level?